It doesn't really make sense (the people staying in azeroth/outland when they could go elsewhere weren't doing it for more exp), but it's understandable. I guess. Shame they have to something unnecessary without fixing the bugs (hunter pets!) first.
Of course, why hunter pets have to level is beyond me. No other pet class has that problem, and honestly, why make us grind out 3 levels? It's not a challenge, it's not fun, and no one that I know of likes it.