Healers are reliant on others in PVP just as DPS and tank are reliant on healers. It's intertwined that way. Yes, we have a couple self-heals but they're nowhere NEAR as good as those coming from a healer. In PVP your goal, like it or not, is to heal yourself and your teammates and get the dogpile of enemy dps and tank off of you so that you can continue to focus on your goal. Throwing in the ability for healers to DPS in PVP would just add another layer of complexity to an already stressful job.
