Please let "respawning of enemies" to Diablo-clones and similar mindless action clickfests. It would be really BAD idea. If you go back to some explorer area, you go there with some clear purpose, some quest. To encounter again the same enemies on every step, it is utterly boring and annoying, especially because it slows you on your quest. I agree that in some areas it may have sense to respawn few enemies (not all!) - like in underground nests or forests where animals and creatures live. But generally speaking respawning is bad idea for RPG.
As Alrik said - RPG is NOT only combat. And RPG world is NOT mere killing ground - why would people live in world populated with such unending hordes of vicious beasts?
