Maybe as a happy medium for the wardrobe for F2P, vs P2P would be:
Add the wardrobe free for all users, however add it to where it is an account wide wardrobe for all premium players, so they do not have to buy a costume a 2nd time, or mail to their alts?
Also allow it to only be used from anywhere for players paying for the subscription, and only at a NPC for free players to be able to use the wardrobe.
Thus allowing all to use it, however the convenience of using it anywhere, for any characters on an account being linked to subscriptions only.