And one enemy might give out 1000XP later on, but there is a limited amount of enemies in the game.
You could say the same if mindreading would cost 10xp and 1 enemy would give 1000000xp I think my point is still valid, the cost compared to what you get at later levels, is pretty small :P
Edit: I read this morning that on FoV there are 2 zones whith monsters that respawn, so xp is not limited there.
