We do have a chest in our room. Two of them, in the form of retainers. Plus the Chocobo Saddlebag. Plus the company chest, if you're in an FC. Plus the storeroom for housing items. You can offload things you don't need via the market board, vendors or the discard button.
And technically, unnecessary expansion of the inventory size does cost server space and development time which could be better used for adding more housing wards, furnishing capacity, glamour plates, glamour dresser space, and other more important things. Our feedback should be focused on those higher priority issues first and foremost, in my opinion.
I will say though, a separate dye inventory in the glamour dresser would be nice.
