The entire circular debate summed up in two posts.
It basically amounts to, "Why should I hold all the responsibility? I want to push DPS, too!"
The answer is you shouldn't! It's designed to be shared between both roles. Tanks weave CDs and emnity skills between their combos, so healers can get plenty of their DPS spells in between healing, in return letting the tank have the breathing room to do their stronger DPS combo, which in return kills mobs faster and giving the healer less mana strain, and time to save a DPS if need be.
It's not even hard to do, guys.