I do hope we get to also see what life is like for some people in Tevinter who occupy the middle and lower classes. Sure, I can absolutely see why some power-hungry Altus magi and Archons would be evil on the whole (if not all of them outright), and those 'important' types of people are usually the ones we see.
I guess most of it is just my reluctance to write off a whole culture as pragmatically evil based on the actions of its most prominent members, who have deep incentives to engage in that sort of pragmatically evil behavior.
Regardless, we'll probably see sooner or later through a later game or DLC. My guess is Dorian won't have many good things at all to say about the Tevinter aristocracy in-game (considering his social standing, or lack thereof), but since his over-arching MO seems to be doing at least some positive PR for the Imperium, we'll probably hear a lot from him about how the Imperium isn't completely full of bad people.
Kind of like how I have to explain to people that no, not everyone in Washington DC is a jackass lawyer or holier-than-thou politician. Other people live here too, thanks.
Except, you know, with slavery.