Quite a bit of discussion has been had on the utter uselessness of the quests for higher level players. In addition, the idea of levelling up basically loses its importance after about Level 35 to 40. SO! Why not make quest tiers like the raid tiers they introduced? As you level up, your quests get better, the items get more and better, etc. You could even offer 2 rare ascension mats for a crazy-hard power level, like 4000 or something. Get creative, it might be a good way to make the quests viable for higher level players again.