That would have been a good option to have, but if they believe the Inquisition has outlived their need for it they only require as much justification as they need to get the nobles to support reclaiming territory now claimed by the Inquisition, which probably wouldn't be a lot, nobles love more land.
Sophia's aid was solicited by Ferelden nobles and she led the Wardens in an attempt to depose a monarch. She didn't leave the order, she was Warden Commander and led the Grey Wardens of Ferelden against a king. Arland may have been a tyrant, but he exiled the wardens because they led a rebellion aiming to unseat him and install one of their own on the throne. The order was exiled because the order failed to live up to its promise of political neutrality.
The Inquisition is not self sufficient, it is reliant on alliances with nobles and the thrones of Ferelden and Orlais for resources and the legitimacy of its authority. Without political allies, it has no authority, no resources, and it would start to lose more and more of its army. Without patronage, they would be in serious trouble.
Wars have been started over less than a refusal to return occupied territory.
Well the way this was presented (at first anyway) was that the Council was only there to raise some concerns and pose some sensible requests. Things only went south when the elven servant and the qunari showed up and the Inquisition was handed the idiot ball for the rest of the DLC. If Cyril and Teagan had hidden agendas from the beginning, then the Council was nothing but a farce, and not worthy of consideration at all.
Is Ferelden in the habit of calling for the destruction of organizations that don't serve their needs? Do they call for the Free Marches to disband? Do they call on Orlais to move away from their border? Have they begun any wars to drive out the Dalish? Have they issued ultimatums to the dwarves of Orzammar to seal up their caves and go deeper toward the Darkspawn so Ferelden can have some "rest"?
Does Orlais really think it's capable of guiding the Inquisition when they couldn't even spot servitude to Corypheus in Celene's own cousin?
If there was ever a time for the Willy Wonka meme, it would have been at the Council, and the quote would be, "Tell me again how you saved the world."
As for reclaiming land. What land? Caer Bronach and some camp sites? Give them back to them. Sulidin Keep and still more camp sites? Fine. Take them. Would anyone in Orlais want some old Tevinter outpost in the desert? I doubt it.
Sophia was denounced by the Order. That means she was no longer Warden-Commander. And the fact that Fereldan nobles approached her shows that Ferelden was to blame for what happened just as much as she was. Were the Couslands exiled from Ferelden? No. Arland exiled the Wardens to spite Sophia. It was personal, not political.
If the Inquisition is not self-sufficient then why does Orlais want them? So they can waste resources on them? And why is Ferelden afraid of the Inquisition existing if they can just cut their funding? And how is the Inquisition merging back into the Chantry any better? That just means your tithes fund the Inquisition instead of the Chantry. The Inquisition has soldiers, merchants, donations from commoners, it offers special services such as closing rifts or mage/templar specific activities, and it also has political connections of its own from noble houses all the way down to Avvar tribes, as well as many secrets. And lets not forget the most important ally and political connection of all, which is Orzammar. Yeah, the Inquisition would do just fine.
But even putting all of this aside, there is one aspect of the game that I think all of us forget about even if only briefly. It's that some Inquisitors genuinely did believe that they were the Herald of Andraste. So what about those Inquisitors? Why is it never an option to pull the holy roller card on these tiny mortal lords? They dare question the Herald of our Blessed Lady? Are they heretics?
I wish there was a quest to assassinate Teagan. Can't stand that ungrateful ******.
I wish there were an option to embarrass his soul out of him. Like if you saved Redcliffe you could say, "I'm the one who brought peace and safety to the people of Redcliffe. I closed the hole in the sky. I fed and clothed your people. I stopped the Mage/Templar War. I defeated the Venatori and saved your castle, all while you scurried AWAY LIKE A RAT AND COWERED UNDER QUEEN ANORA'S SKIRT!!!"
That would make In Hushed Whispers worth it.
Maybe not a quest, but... Did anyone else feel like Teagan's character kind of did a 180? I mean, he wasn't all "the warden is gonna take over redcliffe" and when Hawke meets him in whatever DLC that was for 2, he seemed rather beleaguered by Isolde and the trappings of Arl-dom (or near Arl-dom).
So the way he was all like, GTFO Inquisition... I dunno, I guess I wondered why he would have been the Ferelden Rep for the council thingy, you know, instead of the King/Queen or I don't know, any number of other possible choices? The way the map is laid out, Crestwood is no where near Redcliffe and considering the mess the war supposedly ravaged upon the Hinterlands, wouldn't he maybe be a bit too busy trying to get his arling back in order to worry about the Inquisition?
Meh, maybe it was just me.
It didn't look or act like Teagan. I think they should have used Seneschal Garevel from Awakening. They have the same voice actor. Although him distrusting the Wardens also wouldn't make sense, but that gripe needed to be left out no matter who the rep had been. In four out of the five possible endings for who rules Ferelden, either one or two Grey Wardens rule. So no Fereldan should have a problem with this. I think I also would have liked to have seen Bann Alfstanna as well. But I think the Council should have been more balanced. Like Garevel plays the role of the hard-ass who wants the Inquisition gone, and Alfstanna is the gentle voice of understanding that seems to be open to the Inquisition staying... if certain compromises beneficial to all parties can be made. 
The duel is beyond moronic. It's like having some fringe candidate in a presidential election challenge the sitting president to a duel, shoot him in the head, and then declare that he's the president now because he killed the last one. There's no sane universe in which this completely illegitimate candidate, with absolutely no political support, will be allowed to replace the ruler who has a broad political base of power because of murdering them publicly. It's hard to even articulate how mind-blowingly stupid the very concept of a duel for leadership is in any society that isn't basically Proud Warrior Race .
You don't retain any agency. What a Cousland to rule alone? You can go **** yourself. The debate is interesting, but it's as contrived as anything else - it turns out Loghain is super evil, and did things like sell the elves into slavery or actively torture the children of his supporters. That's as contrived as the Exalted Council, except it all goes in your favour. That's not better. That's as bad.
There's absolutely nothing unrealistic about bitter enemies - through sheer circumstance - finding themselves supporting the same outcome. Ferelden and Orlais are bitter enemies at the Exalted Council. They want the exact opposite thing. But if you tell them both to go **** themselves, and insist on running an independent military and political organization within their own territory while annexing their land, stealing tax payments that (they allege) rightfully belong to them, and effectively carve yourself a fiefdom where people worship you as its divine ruler, they'd have to be stupid not to attack you.
Allowing the Inquisition to exist as an independent is beyond stupid. It's an active threat to both nations.
This isn't the United Nations. Neverra and Antiva are irrelevant, because the Inquisition isn't currently annexing their land or active within their territory. No one is about to start a pointless war with Ferelden and Orlais over an organization that, ultimately, has no benefit to them because of the very fact it refuses to be controlled by any sovereign state.
The Exalted Council is the first time Bioware's come close to understanding how IRL power politics work. People don't get basically persuaded by the uber charisma of the protagonist to do stupid things contrary to their own interest. They carry out show trials to advance their own power and pragmatic goals. That's the EC. It's as badly written as any other instance of politics in a Bioware game, but for once it's less stupid as a concept.
"Might makes right" has been the general rule of the world ever since... ever since. Wulff can explain that brute force is how Calanhad became king. So why wouldn't it be any different in the Landsmeet at that time?
Ruling alone is not a gameplay option. That doesn't mean it isn't a lore option. Loghain did plenty of bad things to increase his own power, and you can either fail to win over the nobles or succeed. In Gaspasser all you can do is either lose completely or lose somewhat, and you simply make the choice to do either one. You can't make preparations beforehand, or present anything that increases your score toward winning. The Landsmeet was worlds ahead of the Council.
No, he has a point. Ferelden and Orlais distrust each other more. The Inquisition could just as easily play them against each other and emerge victorious. What happened to all the diplomatic skills and cunning ability to find secrets (that allegedly existed)? You're telling me the Inquisitor can't talk his way out of a Council that doesn't even have logical points to make?
In any case, attacking an organization that is loved by the people and supported by the Divine is the most foolish idea. A better method would be to try and cut off the Inquisition's funding.
You're mistaken. Antiva and Nevarra are relevant if the Divine deems them relevant, and she would since the Inquisition helps the whole of Thedas against the rifts and other dangers. The Free Marches would also join in, as the Inquisition is active there as well, and the Inquisitor could be a Trevelyan. Didn't Varric say or write that the Inquisitor helped him with rifts in Kirkwall? Oh, and can't the Inquisitor be an ally with Sebastian? Couldn't he save a female Hawke who is married to Sebastian from the Fade? Oh look at all those allies.
Speaking of allies, what happened to Briala? My female elf mage helped her. Shouldn't Briala be pulling some strings here?
There is nothing realistic about the Exalted Council. No way to present evidence or even arguments in favor of the Inquisition. It was nothing but a poorly written excuse to force all worldstates in one direction because BioWare is too lazy to account for more than one.
That's not acceptable to anyone. You have a fiefdom. Just because you recall your levy's doesn't mean you don't have power. And you're actively asking to become the greatest arcane repository in Thedas! After they just dealt with an open rebellion by mages that was defeated solely through the fact that mages had no real political or economic power base, your counter-argument is for them to allow you to fix that by removing the very reason the rebellion failed.
The Inquisition, by default, gives no shits (to quote Spartacus) about sovereignty. We always annex territory in Orlais and Ferelden. We do not give it back. We always divert the taxes that go toward the feudal lords. That's it - the declaration of war, full stop. And that's ignoring the incredible political power the Inquisitor has collected as a divine figure.
Again, it's complete and utter rank insanity for any nation to allow the Inquisition to exist independently.
"Hey, look at the Wardens! We want to be like them. They turned the Anderfells into a puppet state, and have a fiefdom in Ferelden granted to them by the Crown. We also want a fiefdom! But it's cool, because we'll answer to absolutely no one and our mandate extends to whatever we want. We cool?" is an argument that will work with exactly no one.
Those people are all dead, and the world isn't under threat. If darkspawn stop existing, you'll find people running to disband the Wardens. And a fiefdom in Amaranthine was dumb, for all of the reasons enumerated above.
They are free to reject knowledge and help. But as far as doing anything to end the Inquisition, they can't. They aren't powerful enough to do it. They would only throw their own countries into chaos.
No, in my worldstate we sided with the templars. And the Chantry still has templars of its own. Besides, I explained that my Inquisition would have been open with the nations of Thedas as well as with the Divine. Besides, if you think this is a concern of theirs, then why would they accept the Inquisition merging with the Chantry? The "problem" doesn't go away in that case, it just changes names. The Divine, no matter who she is, will favor the Inquisition that bows to her.
An abandoned castle on top of a mountain in the Frostback Mountain range is no annexation. And I don't know where you're getting taxation from. I never saw anything in Inquisition about you taxing anyone. It was always fundraising, selling secrets (with no trace back to you), or rent-a-soldier. At best, there might have been some kind of tax or cover charge on merchants if they used one of your keeps, but that doesn't mean they would not have to pay tax to the nation as well. You write "allow" as if any nation can end the Inquisition.
Um... the argument I posted to YOU about the Wardens is that Ferelden is already known to allow Grey Wardens to operate in their country, and has even granted an arling and possibly a teyrnir to them. Why? Because they saved Ferelden from the Blight. Well, the Inquisition saved Ferelden from something worse, and the Inquisition only wants its mountaintop castle that Ferelden completely forgot about. So this proves Ferelden doesn't care about territory, and logically would not find the Inquisition to be any threat to them so long as the troop numbers stay low enough.
Call it dumb all you want. It happened. The Wardens own Amaranthine. What the Inquisition has is nothing by comparison.