I'm not at the point of needed more room as of yet, but I do tend to store all useful materials I find for a later use, but I don't because I tried before and I ran out of room on two retainers. I ended up selling off the materials and got 300k so whatever.

However I also like to be very organized and I agree that this game's storage capability just doesn't allow you to. No sort functionally or anything. I cringe each time I open my armory chest and see things so out of sort because each time you change a class, the gear it takes off just gets put into the first available open slot and not where you last put it. Annoying.

I'll add that over all this is a minor issue but an issue none the less. I have had to spend a good amount of time in the past to organize my inventory/retainers instead of playing the game. That is not what I'd consider working as intended.