The moogle attire was mainly a bonus for those who attended FanFest last year. People were unhappy as it was that it was made available to everyone via the livestream at the time so I seriously doubt SE would risk the fallout over making it buyable in the cash shop. It was a "thank you" reward for those who took part in Fan Fest, in person or remotely, so if you weren't involved you don't deserve the "thank you"...
Like many of the limited availability items in this game, if you missed it you missed it. It's nice that this game has a small selection of items that are truly rare due to no longer being available. You can't expect to show up late to the party and have everything you missed served to you on a plate.
