It sounds to me like YOU don't like playing a healer in WoW. Doing damage is part of being a healer. You are playing half a spec and complain that this half of a spec isn't the full spec.
I said this once about FF14 but it also fits into WoW:
Every role consists of two parts.
Tanks are one part tanking and one part maximizing your dps.
Healers are one part healing and one part maximizing your dps
And DDs are two parts maximizing your dps.