I'm usually not an advocate of inventory expansion. I believe in the maxim "junk expands to fill the space", and that inventory management requires a little effort on the side of the players as well, instead of just endlessly tacking on more storage space.
That said, I'd love to see an extra Mog Wardrobe. I've got a pretty good amount of storage space open (over 100 slots) and could free up more by sticking things on a Porter Moogle slip. But I have grown accustomed to the convenience of just switching jobs and having gear in Wardrobe, without fussing around with all the storage options. Any possibility we could get another Mog Wardrobe? Its big draw over every other storage space is the convenience of equipping gear right out of there.