If they want an efficient inventory system to learn from, Wild Star's is pretty top notch even if the game itself isn't everyone's cup of tea. They have a dedicated crate for housing supplies, which also accounts for the room needed for the kind of "tinker toys" construction of non-instanced buildings that made their housing system famous, but that extra space could be used for airship components in FFXIV. They also have a very simple way to keep vanity items from clogging up inventory space: The player simply pays a small in-game fee for saving the item's appearance to a list. Afterwards, the player can dispose of the old armor set. Then they need to decide what to do with the old glamour prisms, because they either need to go in the currency tab or just get consolidated into a single, non-multitiered item, or both. They've also been pretty lazy with currency in general with the way they just throw vouchers, ambers, and other currency items into the player's inventory.