I think healers need more kit interactivity (both for heal and dps) and rewards.
Just increasing incomming damage and making curebots instead of glarebots would be pointless.

Look at DPS casters : spells procs for instant casts/upgraded versions ; dots procs ; more complex/interesting job specific ressource and use. Even SMN with it's 2 button gameplay has a kind on "stance rotation" that could be made into something.

Just copy/paste :
-blm kit on whm with cure/glare instead of ice/fire
-rdm gauge on sge sith shield/dps instead of light/dark
-smn summon rotation on sch (with fairies with regen/shield/dpsbuff/mitig specs)
-ast is already busy, so possibly rdm dualcast could help them