DA2's a lot less buggy on my rig too, FWIW. Mostly it's the infamous lag issue.
I've always suspected that DA:O was too long. You can keep people playing longer in a plotless game because a player can just get in and out without committing to much, but Bio games are about the overall narrative. Sort of the difference between a heavily serialized TV show and a more episodic one.
The problem is that DA:O's plot goes nowhere. In between Ostagar and the Landsmeet, you basically have a huge number of filler quests that don't advance or relate to the main threat at all. The whole game is about stopping the darkspawn in Ferelden, but you're really mostly running errands the entire game.
It's the same story structure ME1 used between Eden Prime and Illos. You could add a lot of filler worlds there that don't really advance the plot all that much, and it's easy to lose interest in this type of story.
As much as I'm not a fan of JRPGs, their lengthy story at least goes somewhere.
The problem is that after getting about 15% into the game, you know exactly what the ending will be: stop the archdemon. Bioware needs to use its act structure better and build up to a conflict that isn't immediately revelead in the first 10 hours of a 90 hour game.