It gets rather annoying if, say, the healer requests slow pulls because they are not comfortable with dealing with pulling more than 1 mob just yet (let's say these are HW pre-Vault dungeons) and the tank obliges them and this agreement was said in party chat at the start of the dungeon, and some DPS decide that's not good enough and they start pulling for the tank. That is incredibly annoying, especially in situations where the healer simply hasn't gotten comfortable enough to heal like that.
