It spoke none too well of Udina's competences that he somehow thought that he could establish a Council completely composed of humans and think that not only would the other council races not object but that it would not make humanity's act of sacrificing the Council look questionable as hell in the light of it. There were little sense to that choice while there were sense to the choice in Trespasser.
Also to my memory, you could not become a Spectre in Mass Effect 2 unless a certain criteria was met.
Firstly, there is a great difference, multiple ones in fact, between an organization and a country even you consider both to be morally-ambigous or morally-bankrupt. If the developers are barred from having the player join an organization or working within a country then that closes off a lot of potential ways a story can play out for no decent reason, in my opinion.
Secondly, Solas is presented as the future antagonist and he has made it abundantly clear he is not a god so where are you seeing the old gods angle?
Thirdly, there is a world of differences betweeen a character being resurrected from the dead as a cyborg and a character gaining a prosthesis because they lost one of their hands.
Fourthly, where are you seeing a suicide mission into the Fade?
The point is no matter what you choose, you will get something similar like in ME 2, no one will care if you disbanded or no the Inquisition, just like in ME 2 no one cared if you killed or no the council, which was a BIG desicion at the end of ME no matter how hard you try to make it look stupid, it was in fact a BIG and important desicion that in the end didnt mattered AT ALL.
You could RETAIN your tittle as Specter not BECOME one in ME2, and the only way to do it was to save the council, you make it sound like there is a **** ton of things that you need to do for that to happen which is simply not true and its pointless because no one gives a **** if you retain that tittle or dont which is going to be the same with the Inquisitor tittle.
Tevinter and Cerberus are VERY similar in how they are seen as the "evil" or the "different" ones that no one likes, so of course if the Inquisitor goes to Tevinet no one is going to like that desicion thats the point of what i said, its similar, pretty similar to what happened in ME2.
Solas the main antagonist... maybe you forgot the part where he said that he didnt killed the old gods and that they were locked away in the veil, so when he does what he wants to do the old gods are going to come back.
Who knows... maybe you will be killed anyways and you will need a full reconstruction, maybe you will get some special magic treatment that will give you your hand back and your rift powers, the point is that is similar.
A suicide mission into the fade, well this is pretty obvious, no one has entered physically to the fade besides the Inquisitor and someof his followers... so lets say Solas needs to go to the fade again to do what hee needs to do, so to stop him you need to go into the fade too, you will need to open the rift again to enter the fade and take your team with you with little to no chances of comming back, what could also happen is that Solas makes some stupid mistake or he is defeated by the old gods when he does this and then you have to stop them before they come through the veil, point is this makes a LOT of sense to happen at some point.