I'm bored when I heal because I need more complex DPS rotations

[Nadda]

It is entirely reductive to say that when healers had more DPS buttons in the past.

Well, I've been playing since Heavensward so please forgive me if I don't know about changes for Whitemages before that point but I've been a Whitemage main throughout.

But my Stone became Glare. My Aero became Dia. My Holy became Holier... I still have Assize from Storm Blood.
The only real DPS button I lost was Aero 3 (which is surely missed) but I also have Afflatus Misery now.

So I've had the same number of DPS buttons for the last 4 expansions.

Perhaps you're referring to Scholar or Astrologian?
Again I was open to examples of other MMOs to which to be referred. I want to know what exactly you're looking for.

This I don't really get, how is it a placebo effect? Having a harder damage rotation on top of having to heal the party is definitely an increase in skill ceiling.

Well to demonstrate you actually gave me a good example so allow me to illuminate.

Who cares about the number that Glare outputs? Glare is still boring. I don't care if a newer rotation does less damage or more damage than what we output currently..

You wouldn't care if you did more or less damage than we do currently just using our current toolset. As long as it is enjoyable for you.
The first definition of Placebo that I could find is.

"A substance that has positive effects as a result of a patient's perception that it is beneficial rather than as a result of a causative ingredient."

To you in this case the substance would be giving you more buttons the positive effect would be your perception of enjoyment. Regardless as you yourself put it if you did less or more equal damage as you do use glare.

That would be a placebo effect.

And the reason I say this wouldn't raise the ceiling or change the floor or any architecture wear in. That players are very adaptable to change and if the damage output remained the same - which for balance reasons it would, Healers won't suddenly be doing more DPS than we are now - that the act of pressing buttons would be an illusion of complexity and enjoyment without really changing a thing. It's the same thing broken into multiple buttons.
The reason this wouldn't work for say DPS I assume you might ask after is that the DPS identity comes from their diverse multitude of damaging spells to express themselves with and the decisions they make in using them are core to their role. As a White mage, my diverse multitude of healing spells to express myself with and the decisions I make in using them are core to my role.

That's not to say we couldn't use more DPS buttons but even if it was expanded to say two more buttons they'd have to play an important function past the redundancy of feeling good to press more buttons their utility would play a factor.