Some quest items have such an insanely terrible drop rate that its not even worth completing gathering quests, especially if you are grouped with someone. It takes forever to get the items, especially if you're getting ganked by the opposing faction (seems to happen a lot on horde as alliance always run around grouped or with a 70)

Was in Hellfire last night and literally just kept abandoning quests that required me to gather items from mobs because they simply just don't drop. 30 Naga Claws with someone else in the party? Yeah that's gonna take an hour +

Buff quest item drop rates a smidge.