I honestly wouldn't mind if they removed GCD healing entirely, except for perhaps one tank upkeep heal for lower levels.

Obviously that's a big take, so what I mean is if they embraced healer dps and designed to work with it instead of pretending it didn't exist. Dps would be mainly GCD based. They could add more engagement to that dps (I don't mean rocket science complexity, just make it more interesting), then have healing as something you weave between those GCD casts. This means the role has a decent apm and flows well. Dps neutral GCD's like Lilies (if improved) or Macro/Pneuma would be fine too. They would need to bolster the oGCD kit where it might be lacking (especially WHM) so that encounters could be beaten with just oGCD's.

What this would result in is a role where resource management is actually important. No more blind Medica II spam. You couldn't just blow 3 oGCD raid heals at the first scratch either. You'd need to space out, combine and utilize your tools well and you'd be rewarded for it.

Trying to make Medica or Benefic II or Succor rewarding is an exercise in futility. They'd outright have to stick 300 potency on them. But then you'd spam them more than ever. I think it's time to accept healers are Battle Clerics in this game and try to design around that type of gameplay.