You raise good points that I also noticed while playing.
I would like to add that there are clearly ennemies designed for jumping (the two minotaurs in the underdark are a very obvious example) and ennemies who won't jump even if their life (or that of their leader) depends on it, which breaks immersion (the goblins in the ruins of the temple who stay stuck behind a railing if there's fire in the stairs).
