So one thing I've been frustrated with recently is how cluttered my inventory is getting. I'd like to be able to move my stuff around and make my own categories, that way I could stash away the Proto gear/other useless untradeables and make my stuff easier to find.
It's a rather simple idea: allow players to make their own categories and move their equipment around within their inventories.
While I'm sure that user-customized inventory categories is probably a lot more complicated to implement than you think, I believe that having some sort of storage box would be a good idea.