I don't really see an issue with FFXIV's progression system. I know some players have a problem with it, but that doesn't make it flawed. Why do you feel a capped character has plateaued? And has it truly plateaued? All jobs capped, and maxed out in gear? Got all your EX clears and primal mounts? How about your DoH and DoL? You ever get your blessed tools? How about the one for FSH that VERY few peeps in the game actually have? How's your achievement log? Sightseeing log?

Now, I understand that not all of these activities are for everyone, but if some of these are your thing, can you imagine still trying to get them done while staying caught up while your less interested buddies continue to progress further and further away from you because it's endless? I already feel this now with a level cap because I started late, and my playstyle just won't allow me to catch up to everyone. My activities in the game are far too dispersed.

A merit system could be good or bad I suppose. I see good things because it can keep older content active, but I also see bad as I think it would bring down the desire to level other jobs. I suppose it just depends on how it is set up. It definitely can't impact gameplay, but if a merit system could bring some welcome QoL changes I don't see an issue with it.

While I know you're just brainstorming you have to try to foresee the impact even a small change can have. As an example, merit points that allow increased movement speed outside combat seems benign, but underneath that silky exterior takes away movement speed gimmicks that belong to bard and ninja.

Your posting a lot of content desiring changes to the game, and I have to wonder if you enjoy playing FFXIV anymore dude. Not all change is needed, welcome, or good. While I think the devs should continue to add to the game; this is different than desiring actual changes and the additions you propose will unquestionably change the game.