Selecting a dungeon's pace is a tank's right and responsibility. Gauging a group, deciding what to try, and reallocating focus if things don't turn out as planned. Anyone who wants to pull instead of follow needs to get off their dps or healer and roll their own tank instead. There will always be a bad tank here and there, but on the whole people who dedicate themselves to the role tend to have a good handle on what they are comfortable with and what--on average--a variety of group makeups can deal with. Let them do their freakin' role, people.