I'm sorry, but this post just doesn't make sense (and seems to fundamentally miss a crucial point of the healer woes). Ultimates cannot fix the issue that afflicts dps (and tanks)- if the role is very homogeneous, swapping between job A and job B on an Ultimate will result in a similar experience. This is even more true of tanks than it is of dps, you can literally go into TOP and clear as WAR and then go as DRK and it's mostly the same (invul cd forcing an earlier tank swap p5 aside). I don't think I've ever heard of people proposing Ultimates as a panacea for role/job homogeneity, because it fundamentally doesn't change the problem at all. Even the "wanna press more than 1 button" line doesn't make sense, because while you can play through a lot of content just doing 1-2-3 s dps and clear, you don't have to and are absolutely rewarded for not doing so (you clear much faster, and in a more engaging and fun way too).
The (very wrong) reason why people tell healers to play Ultimate stems from a completely different issue- that the primary role healers serve (to heal) is barely necessary in a large portion of the content. To exacerbate that issue, the only alternative they have is spamming 1 (with a 2 every 30s). They have no other option. Both of these are issues that dps (and tanks) do not have. You can do more than spam 1 as dps (and be rewarded for it). Your primary task (doing damage) is always desirable- to the point that, if it's possible to safely cut a healer or a tank for a dps, it's immediately optimal to do so.
To make it worse, this issue with healing being superfluous is tightly tied to encounter design (good healing is often reactive and somewhat random, which clashes with the typical scripted encounter design XIV has had for years now) and tank design (their absurd levels of self-healing are part of why healers are not necessary). These issues are much deeper and complicated and do not afflict dps. And, in fact, Ultimate does, in a way, mitigate them a bit (you definitely need to heal and mitigate more in an Ultimate than a dungeon).
Now, of course healers also suffer from homogeneity problems. But this is the least of their worries, because their whole role is both incapable of shining through what they're meant to do, what they're meant to do is incredibly boring with no alternative and is much harder to fix. One should add that healers being fundamentally different is also much more difficult to balance (they should still try, of course, but look at P3S to see what happens if you're not careful).
There's a lot wrong with XIV- with casual content being poorly designed (they could return to the Alex lenient dps checks for normal mode, and add small unscripted healing checks to engage the healers), with the horrendous leveling experience and low level gameplay (probably the biggest issue with the dps role) and with the homogeneity of most roles. But just posting some incendiary lines that are detached from these problems doesn't strike me as very fruitful.
Fwiw, the healer problems are literally an order of magnitude harsher than the dps or tank ones. I'm a dps main, but if I had to bite the bullet for one expansion to have healers somewhat improved, I'd willingly do it. The healer role is on life support right now.