When I first started Dragon Age in Origins, I was also Pro-Circle and Pro-templar. But after DA2, learning about magic, the fade, demons, templars, the harsher realities of Circle life, my view on it has evolved. And idk much about TES but their Mages' Guild can't be more persecuted that the Circle of Magi. Thus comparing the too settings is irrelevant; it's apples and oranges.
I'm willing to do the same, if you can give me reason to. Which I doubt.
The point of the TES comparison is that their magic is much, much less dangerous and much less stigmatized than DA's, and even they concede that practicing magic in crowded cities isn't necessarily a good idea. If you add in the much worse stigma against magic in DA to the thing where mages in DA can become an abomination, then that just strengthens my point. This is because the whole idea of my argument is that TES's way of handling magic, which looks a lot like what I believe you to want, doesn't work in this setting.
Or did you mean that the difference between the Mages Guild (which allows you to live wherever you want) and the Circle (which doesn't) means no comparison can be made at all? Because I don't think you have a case there, given that my argument for why that works in one setting but not in another is in fact based on an attempt to notice the salient differences and ask whether the same system is the optimal way to handle both forms of magic. (Which I believe the answer to is "no.")
Connor and Keili are the product of stigma against magic. Connor maybe became psychologically imbalanced when a demon is ripped from him, I'm not sure if he's mentally capable since even Marethari says there would be adverse affects from it.
My point in pointing out why Connor might be the way he is was to show that there's an alternative reason for him to hate himself, in addition to the one you state. Pointing out that there's another other reason doesn't help your argument. Or were you just saying that he might be more vulnerable to being told to hate himself? Because maybe he is, but let's not pretend that that's the only reason why he could hate himself for what happened even if it's not entirely fair of him.
As for Keili, yeah, the stigma against magic probably doesn't help, but it's not unknown for a teenager to hate themselves. Besides, I don't think we're shown any reason to believe the Chantry officials she's currently exposed to are trying to help her hate herself instead of trying to help her self-esteem.
Wynne's faith is derived from an idealized notion of the Circle- a Circle to her only protects and educates mages and the mundane people. That's what she clings to and the hopelessness that it can't get any better. But her idealized notion is based on a lie and since she's been indoctrinated by the Circle and hasn't seen other cultures do something else which could be more effective, she's not worldly enough to know better. The Circle is a prison meant to stifle mages. Even the mages you are trapped with who Wynne would like to believe is loyal and thinks with their best intentions at heart, aren't. Take Adrian for example, she threw her son, precious cinnamon roll Rhys, under the bus to further her agenda and she's part of the vocal mage leadership. You have people like Vivienne who would scheme against you if you don't subscribe to her political beliefs and I doubt she would stick up for Rhys when he was accused of murder as it would force her to fight against templars, The templar leadership are so biased against mages that they do everything in their power to stifle you. For example Lambert, lord seeker condoning murdering Wynne herself. And the Chantry, when has their intervention even led to meaningful change when they are bound by their duty to support the templars or risk civil war? Faith is great but it requires truth to sustain it and though she says she fully supports the Circle, it's based on an idealized version of it not grounded in reality, and her actions speak differently. She allowed Aneirin to run apostate, when her convictions and faith in the Circle system should have led her to turn him in to the templars since Wynne as she claims, believes a mage not supervised by the Circle can be a danger to himself or others. She went behind the Divine's back and sent the results of the research to every Circle showing a lack of trust on what Justinia would do with the information. She fought the templars and Lambert, going against the "duty" of the templars when it is not her place to go against the Lord Seeker no more than it for Irving to stop bad cop Gregoir as you said yourself. Her faith would have ultimately led to disillusionment because it's not grounded in truth. She'd either kill herself, become like Keili, or wisen up and see the Circle for what it is: a prison meant to stifle mages.
This is why I try to limit myself to shorter paragraphs. I'll try to answer all of this if you try not to repeat anything I've already answered.
Wynne's seen the bad in the Circles. She's also well aware that there are lynch mobs outside of them. She does tend to idealize the Circles, and arguably more than they deserve, but in her defense: they were home. Her first memories were as an urchin. Not even a city urchin who could fall in with a gang: she was a country urchin dependent on what might have been the one farm for miles. Someone like her really was lucky to find the Circle.
Adrian threw Rhys under the bus for what you want. She also attempted to throw "blue fire" (which I'm not sure works like regular fire but doesn't sound like a non-lethal attack to me) at some peasants who feared magic for justifiable reasons in order to get them to back off when all that was needed was a Templar's warning before they backed down. And if it did work like regular fire lets not overlook how stupid it is to use it in a peasant building in a medieval setting: those tend to be flammable. If her presence in the Circle is a good reason to not want to live there, her actions outside it and against it are also a good reason for some mages to need to.
Vivienne is in many ways the best argument against your assertion that a scheming aristocrat is no less dangerous than a scheming mage. She establishes herself as a threat by freezing a man who was threatening you with a sword in his place and being more than willing to kill him if you ask it. He cannot defend himself because she is a mage, and according to Cole's banter he's only in that position at all because she's also better at being an Orlesian than he is. If she wasn't married to the idea of the Circle as a place for mages to learn and humanized by Cole seeing her softer side in banter (over her objections, mind you; let's not skate over the fact that Cole is creepy too) I'd find her to be the scariest character in the game not excepting Anders or Corypheus. And if she makes the Circle a scarier place to be? She makes everywhere else she is that too.
But you're also wrong that Vivienne is unwilling to stand up against the Templars. She doesn't say the Templars are always right, merely that standing up to them in the exact way Fiona tried was foolish. And her endgame is that the Templars are firmly under her control, which is scary because it's her controlling them but also entirely necessary since we've seen what happens when they go uncontrolled.
The above paragraph mostly answers your point that the Templars are biased: if they do everything in their power to screw with mages, keep them more firmly controlled.
She did try to persuade Aneirin to go back to the Circle. Which was probably foolish of her given that the last time he was there they tried to kill him, but then that's probably why she didn't hand him over to the Templars.
Going behind the Divine's back was questionable. Not to deny there were Tranquil who shouldn't have been, but the process of curing Tranquil does not seem to lead to reliable mages. They seem to be overly emotional, and that's a bad thing for a mage.
But non-mages are just as dangerous as mages, they just like to pretend they're not because it'd knock them down a peg. They can summon demons. Look at the Harrimans, they summoned a desire demon with out a mage. And the elven Orphanage summoned demons by massacring elves. Despite mages always being looked to as the source of every magical catastrophe, any non-mage can summon demons and create catastrophe since all a demon requires is enough death; and with the amount of elitism and callousness in Thedas, would be easy to provide by anyone with power. Hell dragon and doomsday cults are making a come back. Even the seekers require opening the veil just to aquire their powers, and a spirit bold enough to want to help and crosses over but is constantly stifled eventually becomes a demon. Let's not forget the Red Templars led by Samson and the Order of Fiery Promise led by Lord Seeker Lucius himself. You can bury your head in the sand and pretend that magisters and blood magic is the worse it can get for Thedas but factually it's not.
Lady Harriman is seen with a demon in a Tevinter Ruin. That's not the same as summoning it despite being a non-mage. Boost seems to think she was a secret apostate, as observed by her using magic. The other interpretation is that the demon gave her the magic, which is weird but I guess possible. Anyway, the demon's presence requires that it found its way past the Veil. It does not require that it was summoned, since demons can find their way through on their own in some areas, or specifically that Harriman summoned it without being a mage. (I could swear I pointed all of this out to you last time you used that argument.)
As for the rest of it: most non-mages can't cause enough death on their own to damage the Veil enough to get a demon out. People like Howe can kill enough people to damage the Veil, but he's very much in the minority as far as having that much authority.
As for the Templars: they need lyrium. Mages can use it, but don't need to. A templar who drinks semi-rare blue lyrium can block magic, and pays dearly for it eventually. A templar who drinks the (until fairly late in the series much rarer) red lyrium gets a lot more power than that, and pays much worse for it eventually including their own death. Samson has way more power than that: despite not being visibly mutated from all I remember he can apparently muster the strength to snap a man in half after a several day forced march, but the amount of effort Corypheus had to go to... he had a Tranquil work to seal him into a suit of Red Lyrium that would have killed any other man to wear. And even then, their powers are much more limited in scope than the mages. A mage can cast just about any spell: fire, frost, lightning, summoning spirits with almost no effort where anyone else has to kill a whole bunch of people, and so forth. A Templar who catches a mage off guard cuts off his magic and stabs him, and a mage who catches that Templar off guard does **** knows what to him.
The dragon cults carry much the same problem: their Reavers have increased power and apparently life-steal, but that's nothing to a mage's sheer versatility.
Seekers are much the same as Templars as far as the threat their magic poses, not counting the spirit they apparently court. (Not sure how they do that, maybe they know a place where the Veil is weak? Or a spirit who's already through? I doubt it's because they can bend the Veil at will, since there's no decent evidence that non-mages can do that. At any rate, I don't think there's much risk of it becoming a demon: if there was it probably would have happened, and they seem to take precautions against it judging by the bit where it won't touch impure minds.)
What does the Order of the Fiery Promise do? I know what they want to do, but having not gotten that quest yet I don't know where they get the power they think will accomplish their goals. If they're not a magical threat they have no prayer of ending the world as they desire to, and if they are they probably fall into one of the above slots. (Or have mages, which means they aren't a rebuttal of the Circle system so much as evidence in favor of its wider application.)
Nor do any of these work as an argument against containing mages even if I conceded they were worse. Just because there's a lot more dangerous things out there doesn't mean you should add another to Thedas.