Getting stronger gear is always the goal in a MMO. It separates those who can invest hardwork and time from those who can't and serves as a badge of pride. Unfortunately for healing in FFXIV our healing kits are extremely bloated and become less and less useful as we gear up. It's kind of sad to fight for better gear and then have less fun healing in it. Savage fights and extreme trials are perfect examples of healers being pushed at minimum item level and then having very little to do once the gear score rises. Our single buttons dps rotations then become the focus of our time and the monotony is unbearable for many.
A possible answer to this would be to do away with healing potency altogether and let every ability restore fixed percentages of health. Some may remember there was a time when Scholar's Lustrate restored a fixed percentage of health to the target. Imagine if Medica restored 15% of all party member's health and Medica II Restored 30% over 15 seconds as an example. If every ability functioned like this it would mean a healer would need to map their healing efficiently over every fight no matter how they were geared and use their toolkit more as intended.
A side effect of this would be tool tips that don't have an abstract potency for their descriptions. Healers could communicate exactly how strong their regens are to each other and the party and resist the urge to over heal by throwing everything they have out at once.
Currently, better gear makes content easier and it could continue to do this by its increase to maximum defense for the party and dps output as well. Taking less damage does reduce the healing burden but stronger heals and stronger defense together are already making healing unnecessary in many encounters and that invalidates the whole purpose of healers. If we did away with the improved healing half we could have better balance between the dps and healing aspects of the toolkit.
If healer gear was strictly for a dps increase it would finally make the distinction clear that healers are intended to support their party with personal dps. Healing efficiently would be much more rewarding for players too as it would be clearly evident without gear creep making healing a one button and done event for every raidwide.
Healing with percentages instead of potency would further mean that stepping into high end content as a healer is safer at minimum item level. You know your healing doesn't depend on your gear but your resource management.
I don't think dps and tanks should have percentage based healing tho. Things like Clemency and Vercure should scale with gear while healers alone interact with health in a more economical way to distinguish the role.