Only unlocking (and gearing) all classes, without the need to go 50 everything, makes all your slots almost filled. Agree on have more space.
I've just 50'd a few jobs, but when levelling a new job, now I'm constantly in need to move things from armory to inventory, to be able wear the armory improvements may happen to drop in dungeons.

On top of that, we also have event items to take account, too. I'd like be able to switch to my Valentione set anytime, without the need to stop to a retainer in order get items, and then move items from armory to inventory too, to have the empty slot needed for gear switching.