If it makes y'all feel better, I had the exact opposite experience a couple of days ago, with a BLM who threw a hissy fit because I was going into Sword Oath on bosses in Stone Vigil of all places. Something about overworking the healer (who said nothing the whole dungeon, and no one died the whole way) and losing aggro (I didn't lose aggro on anything) for your pathetic DPS.

The best part is that I, uh, read the combat logs quite thoroughly afterwards, and I was doing more damage than the BLM. I didn't mention that to them, but I did mention that I'm a level 70 SCH/AST and that dropping tank mode is 100% normal and not a problem for healers unless the tank or healer is terribly geared, or the DPS is standing in bad and forcing a bunch of AOE healing. That didn't make them any happier for some reason.