The combat system in this game is flawed at its foundation in a way that makes it difficult to add unique new jobs, make the daily dungeons more interesting, and pace the content in a way that makes it challenging, but not punishing, add fun without wasting the player's time.

Tanks are meant to soak up damage for the party. For that, they need to be sturdy, and they have to be able to keep aggro. They are both in this game, but both in too high a degree. If a tank can keep aggro until the mob dies after just swiping it once with an AOE, keeping enmity is too easy. If a tank can solo a boss in a level-appropriate dungeon after the healer and DPS die, they are too sturdy.

Healers are meant to keep the party alive, but healing is just an afterthought. Most of the playtime as healer is casting damage spells, and with Endwalker, even the cast times of those gets shorter to allow for even easier weaving in of instant heals, which makes healing even less of a challenge, and doing damage becomes an even more important part of the role. If healers even produced decent damage, that would still be not fun for people who want to play a proper healer, but it would make it more tolerable, since you still added value, but if you're 10% of a real DPS player, it's just frustrating. At least WHM has a stun.

Support DPS is not even needed, The little support they do has little impact, and it comes at a cost where the loss of personal DPS is offsetting whatever gain the team might get out of the support.

What this means is, it's difficult to make healing a more active role, and when gear improves, healing becomes less and less important, as tanks grow so durable, they can get by without healing, and just regening after fights. Tanking is boring, because you don't do anything actively. Just hit one thing once with anything, and you can go AFK until it dies. Support with its micro bonus is only important in settings where it adds up, during burst windows in raids, where multiple buffs combined produce a big result, but a BRD or DNC in a 4 man team can't possibly raise the group's performance enough to rectify taking them over a BLM or SAM.

There are other problems, such as "mobility tax" being an outdated model these days, where even BLM has a lot of mobility, and jobs like MNK will have more mobility options than a MCH in Endwalker.

I'm a player, not a game designer, so I won't propose any solutions, but I felt like these things had to be collected and presented in this form at least. Thanks for coming to my TED Talk.