FFXIV was designed, whether intentionally or unintentionally, to have healer gameplay revolve around memorizing boss patterns and responding to them, responding to party mistakes, and dealing damage in-between. These are the three core aspects of how this game is foundationally designed--foundationally meaning not negotiable. You cannot change this without redoing how encounter design is handled on a fundamental level.

Why?

By the very nature of damage and mechanics being scripted in a specific way, the player now knows three things about damage: when it will happen, when it can happen, and when it doesn't happen. Because we have this knowledge, this assures that healers will be promised a certain amount of time to DPS. Healing can only ever be required around and after when damage will happen and when damage can happen. Some of this need can bleed into the windows where damage doesn't happen; however, it is feasibly impossible for a healer to require the entire duration of when damage doesn't happen in order to recover from when damage does happen or when damage can happen. The only way this can occur is if the healer is not healing or preparing for those when and can scenarios.

Healers were designed from Day 1 to be able to DPS. I'll repeat that this CANNOT be undone without redesigning the entire approach to encounter design which also means redesigning every encounter that has been created up until this point. Anyone that does not like this is disputing with how the game is designed foundationally. It's like the situation with FFXVI being an action RPG rather than turn-based. You have every right to not like that it's an action RPG, but playing it anyway and then complaining that it's an action RPG is silly when you made the choice to play that game. The same is true for how healers are designed to DPS. It is built into the game's structure in the same way that action combat is for XVI.

How the developers have approached this truth is the problem. Given the formula of combat being a combination of when damage will, can, and won't occur... there are too many examples of content that is far too gentle on the when damage will and can occur for the amount of healing tools they have given healers. Newer content is finding itself in a better spot, but previous content of all difficulty levels has largely been far too gentle, such as Smileton for casual content, Zodiark for EX content, and P1S for Savage content as examples.

Where healer design utterly fails is addressing gameplay for windows in which damage doesn't happen, which is also represents the largest window of the three windows, especially in more casual content. Take solo content where it is literally 100% of the time as healing requirements do not exist in solo instances to avoid DPS players being locked out. Even though damage does technically occur, NPCs handle the healing for you.

Good job design would dictate that every job, regardless of role, should have an engaging rotation or selection of options available to them during all three windows.

Healers need to address the lack of gameplay provided to them during windows where damage doesn't occur, whether that is direct damage or indirect damage. You can create a healer who can potentially redirect their damage contributions through other players, but the healer needs to have a way of managing that in an engaging toolkit to enable something that creates such an experience. That said, direct damage in the form of a DPS rotation is the dominant answer for how to provide good game design for those windows.

The design team to this point has been actively fighting this reality despite the game existing the way it does because of them. Why they do this is, I imagine, to try and not take any sides on opinions about healer design. But as stated earlier, they cannot truly appease the players who want healers that do not DPS unless they are willing to redo encounter design across the entire game and rework the solo leveling experience to compensate. Trying to not directly tell this collection of players that what they want cannot be achieved is killing the role as we know it in the name of not pushing away a small number of players. The only solution that will genuinely improve the quality of healer design involves accepting this reality and reworking the healers to compliment how this game has be foundationally designed. Until this happens, healers will forever clash with the game's core gameplay.