I don't know, I think it's a complicated fix. It really has only becomes an issue due to the crazy xp you get under raf accounts -- otherwise it's always been fine. Looking forward, say in wrath you're running a ramparts equivalent entry level, level 70-72 instance and a level 80 joins your party -- should your group now get minimal or zero xp because the mobs are gray to the single level 80? They probably don't want this to be the case and therefore just don't want to eliminate it across the board.

Boosting is pretty sick though. I was running my 2+2 RAF accounts through zf last night -- I can't pull large packs because I only have shaman to boost with, but even still, 500xp per mob. That's crazy even if I have to kill them one pack at a time.