I never stated anything about an exaggeration.
My point is that it's a fact that despite having played FFXIV since 2.0 with relatively few breaks and having leveled all craft/gather jobs to level 40+ (at the same time, gathering my own mats the entire way) I've never spent 9 hours to fix up my inventory, and have never even felt the desire let alone need to purchase additional retainers. Therefore, now we have your 9 hours vs my 30-45 minutes tops that I've ever spent in one session of tidying up my inventory at any given time.
I'm not sure how switching the lockboxes to a currency would help with inventory space. They only take up 1 inventory slot unless you're hoarding them beyond 999, there's no lockout forcing you to wait until you have 5 stacks of 999 to use them, it didn't even take me 30 minutes to clear out over 400 of them in one sitting, and that was while I was half distracted with a conversation and running to the npc to sell off the items I didn't need.
Between my personal inventory, chocobo saddlebag, and the 2 free retainers, I have 560 slots, never had a full-to-bursting inventory issue. I'm also not sure what kind of Dewey Decimal system you would have to use to arrange inventory that it would take you 9 straight hours to rearrange anything in this game. I have currencies stored away that aren't even used in the game anymore; old ifrit tokens from 1.0, 1 of every single Yokai Watch medal (even one of the common ones for buying the minions, judge me if you will...), and currencies from Alexander and Omega, all on top of the glamour pieces, fishing lures, craft/gathering mats, etc that I've never had trouble finding when I need it, and I've still never spent even 1/10th of the time you say you and your SO have spent rearranging your SO's inventory.
Is there room for improvement? Sure, there always is with everything in life. I'm just saying your 9 hours of inventory management isn't indicative of the experience for everyone playing this game let alone the condition of the inventory system as a whole. But you continue to make it sure sound like it is.