Lets face it, the GOOD healers are able to provide ample heals and a decent portion of dps. I can hear people reporting me already. If all 6-8 healers in raid all had the mentality of just blindly spam healing and not hitting dps buttons that is a nice little chunk of dps being left on the table. But there is always going to be those 1 or 3 lazy ones that don't even have dps spells on the hotbar. The wardens role is a little more defined with 2 healers. The second healer generally being a shaman. Shaman--debuff/ group wards (single target ward if with tank)/ single target cure/ dps--Warden Group cure/ group heal/ dps/ spot heal raid. It will seem like neither healer is working at all and leaves both plenty of time to cast those long ascension spells. Why over heal/ over cure if you don't have to?