I think it's more of a design philosophy difference between Larian and Bethesda.
From their statements and previous games, Larian pretty strongly believes that once you clear an area, it should stay cleared.
I think changing the game to allow for grinding of infinite XP, even in small amounts, would be a huge headache to implement and an gigantic migrane to balance - look how unbalanced the XP gains are already in the alpha, and that's with limited XP and without quest XP for some quests added in yet.
