So what I'm gathering is all these people are upset over some quests that they have already done and in no way will effect them. I think making these quests easier is a good idea, I'm even for the idea of making it so if you've already completed the quest you can just buy the tail from the NPC. Making it even easier for new people in the future to get help and complete it.
On paper that's sound logic, however, sentimentally (which does retain most if not all value as far as digital property and character development goes in MMOs) it is a slap in the face for those that went through significantly greater and more dedicated efforts to accomplish something which subsequently became a ball-in-the-cup game post patch. Not much different from someone that has spent weeks tirelessly camping Sozu for a Thief's knife only to have it become an item pop and have the market value of which drop like a rock the next day.