It actually provies 7 Storage, and is a neat addition to the Mog House imho, cause it has no restrictions as far as what job you need to be to equip it with. So really, you could mix and match your AF pieces! (If you're like me and want more then one AF job)
The hardest part to obtain is the body, the other pieces are more common drops, but the body drops from BCNMs that aren't popular due to their insane difficulty. If you get a Mannequin Body, then getting the other pieces is fairly simple.