Yoshi-P: "If you want more engaging content, go play Ultimate"

[Payotz]

I've seen this argument a lot, but it doesn't make sense. They've done at least 2 major overhauls in healing during the game's history; one during HW (a shift towards more damage focus), another in SB (removal of Cleric), and another in ShB (shifting to the current paradigm of tons of big heals and super slim, even identical, DPS kits), and that's not counting the AST reworks, of which there have been at least two, and the removal of Nocturnal Stance in EW, and about to be another in 7.0.

They didn't redo all existing content either time.

It's because they've all been designed into having stronger heals. The overhaul that is "needed" is to make heals a lot weaker. Like a WHOLE lot weaker.
Like Cure 3 being 150 potency and only affecting 4 people around you, weaker.

And since a lot of the design in FFXIV is big spiky damage and mitigation checks, then they're gonna have to rework every single raid wide and tankbuster to pass the new paradigm.
They can't be spiky anymore. They'd have to be staggered low damage hits over a small period of time. And that involves reworking a LOT of the fights in the game, including Dungeons and Story Trials.

The only reason why it worked in the overhauls is that they've consistently been making healers and tanks stronger.
Like the only healer and tank that was "weak" on launch was Nocturnal AST and DRK, and that was just because AST actually needed to manage mana, and DRK needed to manage cooldowns.

And if a tiny change like that would "break the game" according to the community, then what are the chances that a complete overhaul would come through?

WoW did a major focus shift from Wrath into Cataclysm because of the exact same problem with their healer design in Wrath (people were running 5 man Heroic dungeons with no Healers because Tanks were so OP), and they didn't redesign all prior content to match that paradigm, either.

Well Cata is essentially a rework of the Old World, so technically, they did redesign a large portion of the prior content to match that.
And there's one thing that FFXIV has that WoW doesn't that lets WoW do that. They don't do synced content.

FFXIV has a vested interest in keeping their old content clearable just because synced content is a major selling point of the game.
It would be bad optics to just have synced minimum ilvl, no echo to be unclearable because of the new design.
"Oh SE ruined healers now!!!!! It's bad!!!!" would fill every reddit thread, twitter thread, forum posts and pf post for like 2 expansions.