I do like unlocking all classes on one character. then again I used to play a defunct mmo that let you have all the jobs, and had many alts.(you can even switch class mid Duty, long as there wasn't combat.)
it also let you have a accountwide storage for specific glamour, as well as Statted Gear.[but only I'd some higher rarities]

That said, I'd want it to fit XIV.
Like adjustments to Relics if you've completed their final step<and or all the Relics of a expac>[eureka could be one of the few/only exceptions, since the journey is kinda worth it.]

I'd definitely buy nearly all the mogstore items if they were Accountwide.(course it would then require a rebalancing of shop prices, but at that point I'd accept it, as long as it's not beyond the edge of reasonable)

The thing with alts, accountwide, and other adjacent things.
as one thing improves, others get affected.
Just as an overhaul of the glamour/armoire system would pay well to such things.

All boats float.

[Which is to say, if all at once, it is undoubtedly a monumental task. but since it's all Interrelated, any improvement or QoL would eventually lower the bar even further. Specially with many adjacent things. and not in the way some imagine/argue in different threads. if they build it to eventually make the task reachable, it will happen. if they don't. they'll hear and reach an impasse of their own making, just like with certain content/activities/systems. being held back when requiring other things to function.]