Sometimes they may feel lazy/tired; I know when I jump on my healer I sometimes don't bother dosing. Why? Because I already have to press buttons nonstop and keep the group moving since I main a tank (currently War but have all 3).

Also most of the time people don't commend me if I go above and beyond what's expected. I had this run where I did dps the entire run, and never let the group die. I didn't get anything extra out of it. I did it because it was fun and I want to get out of there asap.