It's a no-win situation when it comes to tanking in this game. Pull "too little", you're a scrub tank. Pull "too much", you're a troll tank. And that definition will change from group to group. I try to be reasonable and ask what people would be comfortable with at the start of a dungeon with mixed results. If you want to stop tanks from being pull-crazy, the culture will need to change first and that is easier said than done.