(1) Right, but what I mean is that isn't an argument to change past designs. Leaving them alone makes them no worse than now. Even infrequent, that damage would be addressed by a GCD, thus breaking up the Glarespam. And the goal is to make healing in current content more engaging, not in redoing the entire game - your more DPS buttons solution wouldn't help since you wouldn't be getting them until SB or later content, so you'd still be going 60+ levels before you'd see anything that isn't Aero/Stone.
(2) I'm confused. You were complaining that we don't have more to do that isn't damage or healing, then complain that you don't want THAT not-damage thing. If we had fights designed around using Esuna, an AOE Esuna would trivialize them. I agree it'd be nice if we had fights that used Esuna, but fights that use Esuna would mean that we SHOULDN'T have an AOE Esuna. How is using an AOE Esuna in response to a debuff any different than using an AOE Afflataus Rapture in response to a damage wave? It's not. We dont' use Repose/Sleep on bosses as an interrupt because NO ONE interrupts bosses. Tanks have interrupts and don't use them on bosses because bosses don't have anything interruptable, and if they did, a Tanks oGCD would be the optimal tool to use, not a cast time spell that everyone would tell you you're bad for using just like people say PLD's using Clemency or RDM's using Vercure are bad. My point is you're asking for something other than healing to do...and then limiting it from the things we can actually have that aren't healing and saying the only thing you'd accept is stuff you know isn't going to happen. It's a tilted argument from the start.
(3) Solo content isn't tedious to a lot of people. There's zero reason all Healers NEED those. I think the problem here is that you think that all Healer players want what you do and feel the way you do. Many players find WHM, for example, fun and engaging. People solo Deep Dungeons on it, do MSQ on it, etc, and don't find it tedious or boring. It's explicitly WHY I think we should change SOME Healers but not ALL of them, so that both types of player have at least one they enjoy playing on. There's only one Healer in the game that has 1 DoT + 1 Nuke, and that's AST.
(4) When I say I don't think they all need to be changed, I'm genuine in that appraisal. It's not laziness or even familiarity that makes me think WHM is in a good place. I genuinely believe it IS. I think the encounter designs are wonky and that all the Healers should have less powerful oGCD tools. I won't repeat my full analysis here, but I genuinely believe that oGCD tools should be of two types - weak but commonly available tools (largely to augment GCDs, in some cases as quick semi-emergeny tools like Tetra or Benison could be) and powerful but rarely available tools (like when Benediction was a 6 min or whatever CD ability that you carefully planned for or only used in response to emergencies). That is, things you use alongside your GCDs (small/short) or things you save and use for emergencies or carefully planned events (big/long). The rest of the healing should be more GCD based, which also would mean things like MP would actually matter, and Jobs like Casters having that SB MP transfer ability would make sense and allow for skill expression and utility in other Roles as well. WHM MOSTLY has this going for it, with the only exception being that Lilies are MP free, but that's an acceptable compromise to me. I'd like it if WHM's other GCDs generated Blood Lily as well, so that the trade off between Medica and Rapture was MP and immobility vs mobility at the cost of consuming a resource, but that would make it a meaningful choice on the part of the WHM as to which to use as opposed to the automatic decision that Rapture is automatically better, or if it's about to be up, Assize and just forget using a GCD entirely. Further, as discussed in this thread, WHM is the Healer right now that has the least reliance on its spam GCD damage button; an unexpected thing that I don't think anyone really saw coming.
Note that this is also a place where Healers COULD be more distinct from each other, less homogenized and less samey. I liked the WHM/SCH dichotomy of ARR, which worked because WHMs were GCD direct healers while SCHs were more combat oriented Cleric stance with Lustrate/Eos oGCD side healing. The two worked well together and the two appealed to COMPLETELY different types of player...and pretty much everyone was happy with it. Both could clear lower level/casual content, and in hard team content, each had a place and stood side by side while appealing to disparate player types. This wasn't some other MMO, this wasn't 1.0, this was ARR. And it worked. SCH as an oGCD Healer focusing more of their GCD effort on DPS while activating oGCDs for healing, WHM as a GCD healer (which is still is today via Lilies, people just tend not to think of those as GCDs because they're instant and feed into Misery, a damage spell) focused more on party health bars and doing light filler damage when their attention wasn't needed on healing.
WHM is the only one more or less where it needs to be right now, I think. The only straight up change I think it really NEEDS is to make Plenary a lesser (5%) damage reduction so WHM has as many mits as AST does, even if they're different types. This is the single and only area it cannot compete with the other three Healers since they ALL have at least relatively available mit and WHM does not. Once Temperance is burned, that's it, they're reliant on someone else in the party to mitigate for the next 120 seconds.
If I was going to make any more changes, the second change I'd make is for all WHM GCD heals to generate 1/3rd Blood Lily, and the third I'd make is to make Cure 2 a straight upgrade (same cast time and MP cost) of Cure 1. I think it'd be 5-7th change on my list before I would even get into DPS spells, and it would probably be something like make Assize a GCD with a 40 sec CD and 2 charges, and to add a low level "Water" spell that is an AOE CNJ would get around level 15 or so that upgrades to Holy at 45 so low level WHM's would have an AOE tool. (I think of FF9's Vivi's Water spell where it makes a big sphere that floats up then bursts - kinda like Holy does.)
SGE I think is close-ish. I feel like Toxicon needs to be damage neutral so that SGE using its GCD barriers (maybe heals, too, but definitely barriers) can actually generate more of it. Outside of that, a second short duration Kardia it can place on a second target (basically a variation of Synastry/WoW PLD Beacon of Light that lasts for ~3-4 GCDs), as well as an AOE one. Basically give it those tools on shortish (45-60 sec?) CDs so that they can actually do most of their healing with Kardia augmented a bit by Addersgall and have their big CDs be big/long CDs as outlined above, possibly with a touch of pruning. SGE having a damage rotation is a fine thought, and would work well with the extra Kardia options, but isn't strictly necessary for it to be where it needs to be, it's more an added bonus if we're extra frisky.
SCH and AST, on the other hand...are NOT where they need to be.
They are the ones casting their Broil/Malific the most, and they are the ones with weird optimization and battle systems. SCH has Ruin 2 but no reason to use it.
SCH has the most powerful and extensive oGCD kit in the game aside from MAYBE AST yet doesn't use Ruin 2 to employ them nor has a second DoT to use with its lesser need/reliance on GCDs and more free GCD slots to burn. Hell, a 15 sec duration SHADOW FLARE (GCD 2.5 sec cast) would give them SOMEthing (and, bonus points, work in AOE too!), as would Miasma and/or Miasma 2, etc.
AST has the simplest GCD rotation of all the Healers, yet its oGCDs are too powerful to make meaningful gameplay choices with them, and its Card system we've talked about at length needing adjustment. Many people would even agree that AST doesn't need more damage buttons as they'd overwhelm its players, what it needs is a more interesting Card system and a more effective way to use them. It's one reason my suggestion for AST is to make Cards on the GCD to give them a bit more time between all the target/retargeting they need to do, and this would also making having more interesting Cards that require more thinking WORK.
I'm not being a contrarian when I say it:
I don't think all the Healers DO need to be changed.
I think SCH and AST absolutely do.
I think SGE might need some changes but also largely works.
I think WHM is more or less where it needs to be and would take it as-is, though I'd accept a few tweaks that give it more engagement with its GCD HEALING kit.