OP: You seem to have a very narrowminded view of what constitutes a good story. It's fine to have personal tastes when it comes to fantasy, but I think you're wrong to condemn that which doesn't fall within the parameters of what you find good. Of course you are locked into ("raped" is a hyperbole of the most extreme and absurd order) the role of Grey Warden. Games do not have the flexibility that would allow for someone to completely shed any responcibility of what is expected of them in the plot. Your assertion would be like mine that I should be able to usurp the Throne away from Alistar or the Queen. This just isn't possible in modern gaming restraints - only really for the flexibility of the mind in fantasy writing or PnP.
What really touched me with the end of my campaign and was more emotionally stirring than any other games I can recall having played was how my character, a flawed 'moral****' (as the popular term for a morally driven character goes nowadays), did manage to rise to the moment and leave a lasting, positive legacy in the world. Otherwise Alistar is a great King beloved by the people, the Magi rebuild the citadel, Red Cliff/the Dalish/The City Elves all blossom under positive rule. The only truly negative part of the ending was the Dwarves - and they are just so bitter and feuding with one another that it would be impossible not for that to arise.
As for the characters - this is a reality of having to deal with a group of people, let alone a group of people from such different backgrounds. I witness in miniature the same sort of dynamics between the companions of Dragon Age amongst my own friends and am sure that everyone else does too. Now imagine if your group of friends had the sort of varied backgrounds as in Dragon Age.
The idea of Dragon Age being overly grim dark is really not accurate. The closest it gets to the edge of grimdark is the Broodmother which actually saddened me. If you want true bleak grim dark, it's Berserk. It sounds like you wanted a high fantasy fairytale sort of RPG, which wasn't what Bioware was going for in this.
But you got folks who disliked the story, were okay with it, or loved it - like me.