Yoshi P does not have an Infinity Gauntlet

[Sigiria]

Well realistically they can't just add everything people ask into the game. And not only because of ressources but because some people's ideas are pretty pointless or would not be great in a mmorpg.

That being said, when you consider that they once said FFXI was their most profitable game before FFXIV was released. And it was far from being as popular as FFXIV is. Then you can assume that between the base price of the game + the expansions + the monthly subscriptions + cashop MTX + services like world transfer, extra retainers, etc...
This game must get SE a ton of money.
I sincerely doubt nearly as much money as it should is invested back into the game. I'm willing to bet more than 50% of the profit goes to other games and executives. Because that's how buisness work, it's not about quality, it's about getting as much money as you can as cheaply as you can. So as long as the game is not in crisis they'll keep things steady and won't strive to make it that much better.

But to be fair, that's on SE's executives and not on FFXIV dev team. I doubt they have a lot of weight in deciding how much budget and devs they get.