It's not really the monsters so much as it is absolutely everything else. Highlights from my internal monologue while playing the demo:
"Oh, hello voice actor from Icewind Dale! We waking up from the dead today? This'll be the fifth or sixth time I've done that as the beginning of an RPG/Adventure game, but okay. Just don't tell me that we're going to have to kill rats. Oh, yes, there they are, rat killing time, whatever. Now, where were we? Oh, you've written the re-spawns into the game. That's cool, I guess. When does our short mentor die so we can carrry on solo?"