I'm not here to hit you with the shovel of logic, detailing the Life Tap change yet again, so don't worry. My question is on the methods of giving feedback that the WoW community has displayed. Most specifically: Protests.
The Warlocks were a little more creative in their griefing than the Shaman have been. While it hasn't happened on all servers, many of them saw Warlocks summoning, enslaving, or kiting many powerful demons into the heart of Shattrath. Uvuros, Pit Lords, et cetera. Did this non-peaceful protest have anything to do with the devs' decision to make further adjustments to Life Tap? Personally, I somewhat doubt the protest was a direct contributor to that decision.
I don't think that a protest has ever directly changed something in WoW. I don't believe it strikes fear into the heart of Blizzard. However, it does bring the fact that there are issues into the spotlight. Is this the best way to do that? No, probably not. It does seem to get noticed, at the very least.
[EDIT: My apologies for any misunderstanding: I am aware that this protest was unofficial and not widely organized amongst the Warlock community, and I do not mean to trivialize the feedback the Warlock community has given on the topic. It is merely something that accompanied the Life Tap incident that I wished to supply thoughts on, and see the views of others.]