For example, you say more damage buttons is more fun for casual or new healers. Is it? For some it probably is, but for others, it's not. What is a thing many new healers do? Stay hyper-focused on health bars and not even cast damage spells. Probably being way more focused on health bars than they need to be. But what are they NOT engaging with or taking part in? Oh right, damage buttons. So why would more damage buttons appeal to all of them? Moreover, healing doesn't have to be DIFFICULT to be engaging with the healing side of things. For example:
Imagine for a moment a fight with no in-combat auto healing. Every 7.5 seconds or so, the boss does an AOE 150 potency (vs Healing potencies) damage attack. And every 10 seconds, they hit a single target for 250 potency. And that's it. Just pretend. This is MSQ or something.
That means casual healers would need to use an AOE heal every 15 seconds or so (and the more obsessive every 7.5, so every 3rd GCD), so at time 15, 30, 45, 60, etc (or 7.5, 15, 22.5, 30, etc), and then they'd also need to use a Cure 1 every 4th GCD (10, 20, 30, 400, 50, 60) if they're obsessive, and might be able to risk not doing it until a specific target has been hit twice.
That's super lax healing. Someone could just spam Medica and take care of it without a problem. More optimization focused people would spot heal with Cure 1, or save until a person was hit 2-3 times for a Cure 2. It's not HARD, so it doesn't make new healers uncomfortable, but it breaks up the Glarespam since they have a lot of other healing to do.
"But what about oGCDs?"
The game doesn't teach you about oGCDs. Or weaving. Ever watch a super new player heal? They treat oGCDs like GCDs. And, regardless, you only have so many oGCDs in a 1 minute time period.
But the point of this exercise is to more demonstrate how consistent healing needs can be added to encounters that AREN'T uncomfortable for even novice healers to heal. The most novice healer is probably going to address this problem with a Medica every 10 seconds, or upkeeping Medica 2 every 15 seconds and occasionally spot healing someone with Cure 1. Hardly overwhelming. It's ENTIRELY possible to increase healing needs in even casual content without making new healers run for the hills.
...moreover, that entire argument is predicated on the thought that new healers AREN'T afraid of damage rotations. Interestingly, no one that proffers that argument ever justifies that assumption other than, when called on it, a hand-wave about how "if they don't do enough damage, it doesn't matter because no enrage", failing to explain how a healer TOTALLY NEW TO THE GAME, who doesn't even know what an oGCD or weaving is, is supposed to have arrived at the conclusion they don't need to do any damage or engage with this DPS kit and shouldn't feel bad or bothered by not touching it at all.
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I think the fundamental disconnet is what people find fun.
As a Healer, I've never found damage buttons fun. It's why I don't play DPS unless I need to and rarely play Tanks. "Oh, I perfectly pulled off this burst opener and did 500k dps. /yawn How was that different than last expansion where I did 230k DPS doing the same thing?" I don't get a dopamine hit from that. It's not fun. It's tedious.
Some people enjoy it. It's the reason I propose the "4 Healers model" because I explicitly recognize that.
What boggles my mind is why the people who like DPS (but want to play Healers) arguing the contra position seem incapable of realizing that some people GENUINELY don't enjoy pressing DPS buttons or seeing red numbers on the screen instead of green numbers. Like, is it so hard a concept to believe that some people legitimately don't find DPSing fun? Why is this such a hard ask to just acknowledge?
That is, for casuals (okay, I'm more mid-core, but same thing for the purpose of this argument; I only VERY rarely do Savage content and only do a bit of Extremes), not all of us find it "fun" to press damage buttons. Therefore, "Healers should be fun regardless of the difficulty level of the content" isn't solved by "more damage buttons". "more damage buttons" isn't, as it turns out, "the argument in favor of casual healers".
Indeed, most of the people I see make that argument (most, not all, but most) are people that are Savage raiders complaining about THEM - not casuals, hardcore raiders - being bored. It's "the argument in favor of hardcore healers", not casual ones.
Most super causal players seem to enjoy Healing as it is right now, shockingly. I find causal content pretty enjoyable right now, honestly.