Healers need an overhaul

[Rilifane]

Yea, that's kind of what it boils down to. Healers are like toupees, you only notice the bad ones. The ideal healer just quietly does their job of negating any unavoidable damage and you don't even notice that they are doing that unless they are bad at it and let you die.

That's why I think in order for healer to be a reasonable role in a more casual game that isn't comfortable just making content straight up impossible without an amazing healer you need to have some kind of way of translating overheal into additional damage. Currently that's done by making healers attack instead of heal when everyone is already at full health. The issue with that is that because damage is a secondary role for healers their rotations are kind of bleh.

I would prefer a mechanic where the extra damage comes from more healing, like having the ability to build up some kind of overheal resource that gets spent to deal extra damage, or being able to pulse any healing that exceeds the targets hitpoints to nearby enemies as damage, or something like that.

Please no. This is probably the worst way to solve healer issues.

Rewarding overhealing with the only thing that really counts in this game, namely damage, is a terrible idea.
What gives healers the tiniest of skill ceilings?
Knowing when to heal but, more importantly, knowing when not to heal.
The former is easier to see than the latter. Low HP bar and aoe cast? Heal.
The latter, however, requires keeping an eye on more things: how much mitigation does the party currently have? Are regens already ticking? Does the co heal prepared a heal to use any moment (Summoned Seraph, Star, Macro buff on the party, Plenary applied etc)? How much damage does this attack do, is the current HP pool of the party enough and how much time is there until the next damage? Does someone have a vuln stack (or multiple) and needs extra attention to survive?

The key is finding the balance between healing as much as necessary to keep people alive and no more than that and use the rest of the time to actively dps.
The moment you reward overhealing with damage there is much less thought to healing because you can simply heal all the time without any coordination whatsoever because overhealing now translates into damage. Please don't give all those Medica II bots out there that use it 4 times in a row when everyone is already at 70%+ after the raidwide went through even more reasons to defend their abyssmal and wasteful gameplay.
Besides it might result into a different way of chadding the co heal: wait until they healed and then heal when everyone is full HP because now you get a damage boost. Yay!

When we need is meaningful downtime gameplay that has some variety and identity to it and requires a function brain to maximize in the form of more dps-related buttons and preferably synergies tied to them.
We've been treated long enough as we don't have a functioning brain, making overheal translate into damage would be the worst offender yet.