"Hubris seems to be a huge issue with most mages. Even Anders has it to the point he won't listen to reason either. That's why he lies to Hawke because he knows what he plans is wrong and he doesn't wnat him/her talking him out of doing what he is going to do."
So, is it any coincidence that there's a massive Pride Demon named Hybris sitting underneath all of Kirkwall?

At any rate, I see Kirkwall as a trainwreck from start to finish. In Ferelden, we saw mages being taken from their families at a young age and forced into the Circle, but we also know that mages leave the Circle temporarily from time to time to do something or other on official business. We see a Knight Commander and First Enchanter who are genuinely trying to work around each other and not directly at odds. We run into plenty of mages who aren't evil corrupt blood mages,
But then, Ferelden's Circle isn't in reality a giant prison where they lobotomize you for looking funny like Kirkwall's seems to be have been because everyone assumes that you're guilty until proven innocent.
In Kirkwall, you never see mages outside the Gallows unless they're in hiding or have some kind of powerful protection to keep them from being frog-marched to the Gallows and nice, stuffy cell. It would have been bad enough that Meredith is clearly a dictatorial, controlling tyrant, but she also seems to have gathered the very best of the worst templars under her command. Let's face it, when Cullen is a reasonable guy, you know you've stepped into a world of true zealots.
And when you isolate a group of people so totally from all the rest of the world, they start to behave as if their little ivory tower of rarified magical academia is all there is to reality. When all you can do is study without having to really see the consequences of that study in a real-world manner, does blood magic start to seem unreasonable? Look at today's college profs, they spout all kinds of crazy, impractical stuff because they have sequestered themselves in their ivory tower world by choice and have forgotten what the real world is like. Things that look good on paper or seem sound in theory seem a lot less dangerous. In short, you have an entire class of very powerful people who lack any sense of real perspective.
I kept telling myself that it was the mages' situation in Kirkwall that was poisonous more than the realities of their gifts. After all, two of the most important people in Hawke's life (father and sister) were mages for years and never once succumbed to temptation. If couple of apostates can remain uncorrupt, then it's clearly not the mages themselves that are pre-disposed to corruption. That's when I start examining how their day-to-day existence is different. Basically, they're a bunch of sheltered academics who are being treated with enough suspicion to make paranoia and fear major parts of their everyday lives who have no concept of life in the real world and are being pushed into desparate actions.