Regarding the whole morality issue, I think it’s pretty clear that from both a modern western and an Andrastian perspective, particularly a Ferelden Andrastian point of view, both slavery and blood magic / blood sacrifice are immoral.
Players are assumed to automatically take a ‘modern’ moral attitude, and the setting enables and encourages this as well. Even if your character is not a practising Andrastian 'in your mind', he or she is likely to have the same or very similar moral attitudes. Neither the Qun nor the Dwarves seem to practise or condone blood magic or slavery.
Or in other words: Both from our modern western point of view AND most Thedosian points of view, Tevinter, or at least its ruling elite and socio-political system, are morally repugnant.
Exceptions like Dorian allow both Bio and some of the pro-Tevinter fans to claim that the rulers and their system, not the people and their culture, are effectively evil. Which saves everybody from the potential embarrassment that the ‘most decent’ country from our point of view is ‘White America with swords’ aka almost lily-white Ferelden, and the most evil ‘Graeco-Italian Mediterranean-inspired and vaguely brown’ Tevinter.
The existence of this moral dualism in the setting itself – modern western morality in Andrastian and Ferelden guise and an extreme opposite in Tevinter – makes it very difficult to see the latter as a ‘normal’ society. While the Qunari and the Dwarven societies and ideologies have some objectionable characteristics, none of them offend our modern sensibilities as much.
This is very different from a setting where all societies are thoroughly flawed from our modern western point of view, but which mostly avoid behavioural extremes (medieval Eurasia), or where all engage in them to some extent (ancient Eurasia, Precolumbian America).
A game in a setting like Precolumbian Mexico, or a fantasy setting derived from it, would mean that slavery and human sacrifice are a general fact of life, and these would lose much or even all of their modern moral ‘load’. I don’t know if anyone here has read the novel The Luck of Huemac, by Daniel Peters? The main character is a thoroughly moral and likeable person, but acts and thinks in the context of his society. While he is not a fanatic or a particularly bloodthirsty person (he is rather ‘moderate’, which helps the reader empathize with him), he does fully participate in his culture and society, including the sacrifice and cannibalism.
Likewise, in HBO’s Rome, the main characters are likeable and basically decent, but they also clearly operate along different moral guidelines that differ considerably from ours. Lucius Vorenus, at least in season I, is fairly rigidly honour-bound and is clearly a ‘moral guy’ (partially even from our modern western POV), but he also has a bunch of Gaulish captives he intends to sell into slavery. When they sicken and die and the only survivor is a little boy, he is greatly distraught. Not because his captives died, but because he basically lost the income from his share in the Roman war booty. Likewise, he doesn’t bat an eye when he has to torture Gaulish captives to extract information. His moral system does not include soft-heartedness towards ‘barbarian’ enemies.
You’ll see none of this in Dragon Age; it simply is not that kind of setting, nor is BioWare willing to go there. I think that’s perfectly understandable, they aim for a large, broad audience and their games are played by teenagers (regardless of rating) as well as grizzled veterans. They aren’t ‘family shows’, but they are not HBO territory either. They probably come closest to movies and tv series intended for teenage / adult audiences, with plenty of not-too-realistic violence and maybe a sideboob or two.