It would be a very nice to have as well as being able to have a above your should perspective. Would really give the game a different immersion feeling. As you said like NWN. Not expecting it, perhaps modding? Maybe something later on added.
The game's artwork and especially gameplay isn't really designed for it, though. That's why there's a fixed camera angle - so the art designers could save time (and therefore money) by not prettying up different corners.
