And I say this as I think of how repulsed I always am at noticing my co-healers in most fight content doing the absolute minimum required of them (i.e. not spamming Stone/Broil/Malefic like any decent healer does). Some of this may have to do with their lack of skill, but a lot of it has to do with how healer damage is structured.
Most damage in this game - raid-wide, single-target, or tank-focused - is predictable. Most instances do not have variable damage numbers and do not require the healer to babysit a particular party member or more in case something unpredictable kills them. Even when a boss randomly chooses a target (Prey in O7S, for example), the game provides healers with enough time to plan their healing and then go back to spamming their mind-numbing, filler damage spells. Aside from making sure a party can survive damage at certain points in a fight, the only way a healer of any job can contribute to the success or faster kill of a fight is by spamming a boring damage rotation.
As for actual healer damage roations, all 3 healers share some common things to contribute to party damage. A single-target damage-over-time, instant-cast spell, a single-target "filler" bare damage spell, an AoE spell, and 1 or 2 other nuanced abilities that can also do damage (Assize, Earthly Star, Energy Drain/Ruin II). Aside from the last set of abilities I mentioned, these damage spells do nothing but...damage. They do not interact with the healer's kits, and they are simply there. To a new healer who is learning the healing paradigm in FFXIV, this does nothing to teach them how fights are structured. Damage spells have no cohesiveness with the rest of a healer's kit, so how is a new player supposed to figure out that a healer is actually a DPS with a boring rotation who is supposed to heal at specific points in a fight? I say this unironically because that is how a healer feels to play currently.
That's why, SE, in order to make healers more interesting, a healer needs a way to contribute to raid DPS without resorting to their own personal DPS. Astrologian almost hits that mark - they can choose who to use Balances on if they don't Royal Road them - but outside of that, they still resort to spamming Malefic over and over most of the time.
White Mage, for example, should have buff spells like Bravery, Faith, or Haste (if Time Mage doesn't make a future appearance) to make up for the actions it lost with the Action Role system. All healers in the first place shouldn't have to spam a singular spell in order to perform better. They should have varying means of party DPS contribution that still shows skill expression whilst emphasizing supportive/healer capabilities.