Just some ideas to add a little more fun to the game.

Global Weapon Glamour
Similar to clothes that all classes can apply to their glamour, it would be fun to have a pile of fun items that would replace the weapons for each class.
(ex. stepladder, tooth brush, umbrella, tennis racket, fish bowl, bucket, fly swatter, rolling pin, bowling pin, bowling ball, soccer ball, folding chair, branch, belt, giant hammer, book, rubber chicken, etc. - the list goes on and on!)
It would be a fun way to revitalize some of the glam and new things for players to fuss around with. It'd be fun as a warrior running up and smacking the boss with a folding chair or rubber duck xD

Glamour Effects
It would be fun to have a new profession that allowed adding glow effects to armor and weapons.
Similar to the Augmented Cashmere Robe of Healing that applied spiral sprites around the robe, it would be nice to have several dozen effects that could be applied to glam.
ex. Fire, water, lightning, orbs, lights of different colors, sparkles, fireworks, sad rain cloud overhead or lightning cloud that randomly strikes you etc.
It could be a limited crafting profession, since everything would be cosmetic only, much like melding, disenchanting, digging, etc. that could be taught at a certain level without the need to level other crafting jobs, or just an addition to the dyes.

More Glamour Plates
The addition of glamour plates in Endwalker was great, to say the least, but I was hoping for more. You could literally quadruple the amount of plates and still fill them up easily.
There is currently 15 (8 in row 1, 7 in row 2), while there are 20 Jobs and 11 Disciples (Hand/Land) for a total of 31 jobs, and after Dawntrail, there will be 34 jobs!
There should be enough glam plates to cover every job available.

Link Minions and Mounts to Glamour Plates
A lot of times, I use a specific minion and mount based on what role and glam the character is portraying.
It would be nice to have a slot for both a minion and mount, and an action general menu button that would be linked to summoning said minion/mount while that plate is active (the button could default to last summoned minion/mount if no minion/mount is linked to said glamour plate or no glam plate selected).

Multiple Minions
The ability to summon more than one minion at a time - maybe up to five? Just to have a little entourage that follows you around. Plus the ability to duplicate the minion to have multiple of the same minion.