I think the big issue here is that while they didn't WANT to do it, they genuinely saw no way out. Healing balance and gameplay has been an incredibly touchy subject over the past 3 and a half years.
I've long advocated for switching the tank/healer meta completely. Make MP management a real thing and then pepper in one other management factor per job. Give encounters more rapidly incoming damage and give healers tools to handle them more efficiently and more quickly, allowing for them to choose how to handle it. It's easy, but expensive to burst heal a tank from low HP to full. This allows coordination between healers, if one is destabilized (i.e. low on mana) they can pivot to healing slower and letting the other healer handle the critical components since they have more margin for error.
To supplement that, let tanks have control of their durability. Not with some bland toggle switch or 3 minute cooldowns, but actual effects and oGCDs and some kinda rotational mitigation where they have choices on how much damage to sacrifice for additional durability to help stabilize healers. Not like a HW/StB situation where 100% offense all the time if capable, but real consequences for making mistakes. Not instakills, but things that ramp pressure up.
Naturally this requires a significant overhaul to job and encounter design, but it scratches the more dynamic itch I've been asking for.
For instance for SCH - you could treat the fairy as a healing battery. It does smart healing itself and has it's own MP (and ways to replenish it and burn it), but can also be used as a Innervate type of effect to give the SCH or other healer a burst of MP at the cost of the Fairy's effectiveness. That could be that jobs management aspect. WHM could have things like where the more HoTs actively rolling enable faster cast times or more efficient casts, so trying to keep that is optimal. AST - could have a reworked card system that isn't booty (no input here no solution). Sage could fill a DPS ish niche like Disc Priest where casting offensive spells grants free or reduced cost healing/damage and vice versa, but pending health and stability would have to sacrifice it's more methodical and efficient playstyle for the sake of the pull.
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StrawberryZebra - Just some ideas.