The better the Party is at avoiding mechanics, The less work a Healer has to do.

Its the only Role where the performance of the party directly impacts how active you are.

Tanks always need to keep enmity.
DPS always need to deal damage.
Healers ... Don't always have missing Health to restore.

That right there is what i would change. Our healer toolkits are full to the brim with useful and niche tools to cover any situation we find ourselves in. The only way we get to use all of these tools is when shit is going sideways and people are taking enormous amounts of damage they should otherwise be avoiding.

We absolutely do not need HARDER hitting mechanics. That doesn't solve anything.
For as long as incoming damage is on a script, we Healers will always have deadzones in our Role gameplay.

So break the script. We know the devs have tools in place that allow them to specifically single out Roles for mechanics. We need sporadic, dangerous damage going out to the party with enough frequency that oGCD cooldowns simply cannot cover them all.
It'd be fine to keep some of the scripted damage since fights need to be learnable and not subject to RNG wombo combos, but that scripted damage needs to be interspersed with random damage, either party wide, role wide or singling out party members for hits.
Busters need to be used more frequently at odd intervals so Tanks wont always have their "Anti Buster Button" there to take it every time.

Give me reason to watch the party list like a hawk. A reason to be ready to tap a Heal into someone at all times.
I want Cure/Physik/Benefic to be used as GCD 'fillers' instead of DPS.

Weaving some damage in amongst all the hits the party takes would be what separates Healers from Excellent Healers.