if you want to change the heal in PVP, then you have to change heal in PVP and not PVE, because in PVE healing is totally fine from both WHM and SCH. none of the particular WHM or SCH abilities have to be nerfed.
as a healer myself, i do agree that they should do something because everything now is just too much priotarized for healers, a simple 20-30% heal debuff on everyone in PVP constantly would decrease everything by a bit and less people would QQ.
while there is still a lot to argue about, because if i get a good bard on me, most of my heals if not all just get constantly interrupted. but still the PvP shouldnt be so much focused on getting healers down, and a healing debuff would just do fine with it.