Pay for your inventory.

[Catwho]

I also wanted to mention, for those who didn't play FFXI, that your storage and extra AH slots were additional characters in that game (known as mules) and each one cost $1 extra on top of your sub fee. Retainers became a thing because SE realized that's what we were doing, so even in 1.0 they just went ahead and gave you one to start. (And you had to physically place them in the game so people could examine them, until they fixed that with the market ward search engine. 1.0 was broken as heck...)

Thus, SE charging for additional storage space and additional slots on the AH is nothing new to the XI veterans.

[Sho86]

I also wanted to mention, for those who didn't play FFXI,

If we're gonna compare to XI's inventory, then they need to have a ton more space for items per character. The starting inventory was lower for sure, although could be increased greatly over time, same with MH bank, then added the Aht Urhgan bank. Then they added what, two or three extra satchel/bags that equal your main bags current gobbie bag expansion. Add on the fact the items in your MH were more than show, they each held a specific amount of storage. Top it off with numerous NPCs in the cities, typically Jeuno, that held your gear sets for slips, which typically reside in your key items without clogging space.

As far as materia/SB data, would be the same as signed items in XI that get put into NPC storage, erased down to basic item. The only advantage that couldn't be expanded upon would be the AH, which even after I quit I believe they expanded more from the original 7(?) limit. So in the end, you seriously didn't need that many extra characters for mules. I personally had two extra characters, both of which were alts and not bank stores - with each holding their own gear sets.

Edit: Oh also forgot that "wardrobe" or something-another that came out after I was gone, which stored a ton of stuff.