Yes, in D3 they did this and I think pre expansion was there too regarding the increased item drops, etc…
But they are now being pretty vague and its dissapointing.
I mean, why would someone go from Normal to Penitent when its only double XP but things take 4-5 times longer to kill?
But if the increased loot is there, then it would make sense… at the moment I am leveling faster in Normal.