In trying to work with XIV's existing systems, I'd LOVE the glamour dresser to be able to hold its own stock of dyes. That way when I'm spending some time in there, I don't have to run out and grab or craft a dye that I thought I'd try on a whim.
If we're moving into dream territory, I'd love for them to implement more of GW2's style when it comes to the dyes. In GW2, they have over 600 dyes to collect, and you only have to unlock them once. After that, they're just added to your dye palette and you can apply them with a click of a button (for free).
picture of the UI if anyone is curious
Back on topic though, my main annoyance is how long it takes to add/remove items and to swap between the tabs.
I do think that the game as a whole needs a major inventory overhaul (add specific storage for materials, dyes, bait, tokens/currencies, etc) and reduce item bloat, but I don't know if I'd include a larger FC chest in that.
When I was still in larger FCs, the chests seemed to collect a ton of random junk that really had no reason to be stored there. Results may vary though as it would depend on how involved the FC is in doing group things together (crafting, workshop crafting, helping players out with <whatever>, etc).