What I always wanted to see in a similar game is something like this. You have certain areas where enemies sit and when you kill them for the first time, you get your normal exp. When you return later in the same place and kill them, you get NO experiance whatsoever.
Why something like that? I said that I don't like to grind my characters but I also hate empty worlds. It would be cool being able to return to previous areas and see some life there, so that the world after some serious gaming won't feel dull and empty.
I understand your point of view, and I have seen a similar thing in Sacred 1.
However, I don't want it. If enemies are dead, then I would like to see them dead.
On the other hand I don't like empty worlds as well - and I think there should be neutral NPCs for that.
So all in all I do hope there will not be any kind of respawn.