Actually, they have been making season items sellable via the MB that were once Marketboard Prohibited.

Items include, but are not limited too, Starlight Sentinal trees, Paissa Doll's, Cherry Trees etc. That's why you'll get many players that buy "extra's", store them on their retainers and then sell them a few months down the line for eggstraordinary prices. When they add them to the MB as an item they get unlocked.

I'm not sure that they would do this for barding however. This is more something I would expect them to put onto the Mog Station. I think they had the old Christmas barding on there at one point?