I think you're right. It is a terribly ambitious concept. And, to be fair, even if imports are done correctly, there's still a chance that people like me are annoyed because it could have been even more extensive... or because an NPC whose marriage choices were checked by the game happens to make a quip I dislike.
I'm not being sarcastic when I say it probably is for the best if there's no further importing because in this case, it might be better not to try at all than to try and fail.
I don't believe that many people would have truly hated it if there hadn't been any cameos of Origin's characters in DA2; it was only when they acted wrong or should have been dead that people took notice.