Thanks for showing the desire to hear directly from the player base like this, it's really appreciated.
Here are the things I'd like to see in the game.

1) More defined role for THF: Currently DNC outclasses THF in almost every way, there's almost no situation where you would want a THF that you wouldn't prefer a DNC. Whether it's soloing, or contributing to a party, the job of THF is basically reduced to a single job ability, Treasure Hunter. I'd like to see that change.

2) As many have said before, tank jobs are largely ineffective because damage dealing jobs can generate both damage and enmity more effectively than tanks, once the cap is reached, tanks serve no purpose. As a consequence many abilities on other jobs intended to support tank jobs, are largely useless as well.

3) Sense of progression: Many things in the game are random, requiring repeating actions for a chance at success. This leaves open the possibility of horrible luck for individual players, which can be a frustrating game experience. A guarantee that a goal will be achieved after some maximum number of repetitions provides a more satisfying game experience even if that number is high. One will never feel like ones time towards a goal has been wasted since there will always be progress made. This is somewhat similar to what is done in the new Nyzul Isle content, or even in Abyssea/Magian where instead of random gear drops, players collect items from monsters guaranteeing that they will have the gear they want after at most a set number of NM kills. The Inside the Belly quest and very rare drops would be good places to implement this.

4) Focus on casual play. Add more content that can be completed with 1-4 players like Abyssea. Don't have story content that requires more than 6 players to complete. Content like Dynamis, Limbus, Sea, Sky, and Einherjar had almost no story to them so if you could never join a large linkshell to complete the content, you don't feel like you're missing out on a part of the game. Voidwatch has story content difficult to access for casual players since there's no motivation for players to repeat earlier missions.

5) Inventory: New items introduced into the game outpace new storage solutions. We need more space for stuff or different mechanisms for storing it. Also, I cannot decorate my moghouse the way I'd like because the benefits of moghancements and elemental auras are too good to pass up, and any item of furniture I add, takes up a valuable slot of mogsafe storage

6) Ease of transportation: A lot has been done to improve this area, but getting around is still annoying. Kupopowers Ease of exploration, and swift shoes should be permanent parts of the game. After reaching a certain level, moving around the game world should not be an obstacle or inconvenience for players.