I don't think the main problem of DA:I when it comes to being the dark fantasy it should lies really in the "what" category. Yeah, you're given much less opportunity to be evil, but there are lots of dark elements in the world, even dark consequences of your own actions. The problem is presentation. Dark things mostly happen off-screen or are glossed over, really. Imagine if you were actually challanged with additional hints concerning the fate of Redcliffe and its mages if you don't do something - but it's hardly mentioned. And when the mages/templars attack Haven, they're a faceless mass of enemies, you're never really challenged with the fact that it was your leaving them to Venatori that led them to this situation.
However, I must say that I wonder how much the climate of the game would change if they just dropped those bright and colorful MMORPG-like world for something colored differently. Just that - some different colors, more appropriate for world torn apart by war... I believe this simple change would make the whole game significantly better.
Oh, and as for being pragmatically evil in DA:O, you had lots of opportunities. You could literally let a bunch of elves be taken as slaves in return for incriminating documents. Or you could have them killed for some neat stat bonus, if I recall correctly... And generally there are just some choices (like the Anvil) good people just don't make. And, btw, that was the main thing that made the evil path so good: evil doesn't usually mean "monster for no reason". It usually is "my reasons justify ANY means". and that's what good evil characters are all about