Before you immediately shoot down this idea give me a moment to explain myself. I've been struggling with maintaining investment and interest in the game for a long time and I've brainstormed ideas with friends and such about my own hypothetical ways to fix that. I've had a lot of ideas, some of which I'll briefly touch on here, but a common problem is simply one of "This idea will make some people happy but upset others." Pleasing large numbers of people in a game like this is a difficult balancing act, especially when you start talking about reworking chunks of the game. You're inevitably going to upset people. Blue mage gave me an epiphany that made me realize the solution might not be as difficult or impossible as I previously thought.
I've been playing since shortly after 2.0, and even as far back as midway through Heavensward I was starting to feel burned out. Stormblood got me back into things but ultimately I ended up giving up again once the treadmill of content started up again. For me the endless grind of getting new gear in order to do new content to get new gear had gotten very old and I found myself distancing myself from the game. This is a sentiment I've heard echoed from a lot of people I know who are themselves leaving the game.
I've put forward ideas in private. Ways to reingage players in the long term. Most of them are focused around reworking the gear and ability system. Bringing back things like meaningful builds and subclassing, skill trees, passive abilities, and gear that doesn't become obsolete. Maybe is has things like unique effects attached to them rather than larger numbers so that you could use them based on your build. Cutting back on skill bloat by limiting how many skills you can have active, giving you free respec options so you can try a variety of builds, etc.
Granted, this is a very basic idea. It's much easier to say ideas than to actually make them functional. I recognize why the system is at it is, too. It's much, much simpler to balance things when there is less variety to it. It's also much more accessible to a new player when your options are more limited. And, heck, some people don't WANT to have a lot of choice for any number of reasons. That's ok too. There is nothing wrong with that. Even that is ignoring that the game is a little too established at this point to go through a major rework of its systems. Previously I had suggested a sort of prestiege mode. Instead of increasing a level cap you might get a new tier of levels with a reworked system in place. That way new content going forward could use that but if you went back to old content you'd use the old system. On top of that I thought maybe to preserve accessibility there would be limits in the way a new skill system or job subclass system worked. All of this had issues however, and all of it bumped into the problem of not being able to make everyone happy.