I'm still strongly on the side of the Moogle Attire should have had a pom color change similarity to the Moogle Cap receiving the pom change. Just like you pointed out it seems extremely odd until you go and read the fine print.
I am assuming it ultimately comes down to legal recourse of why certain items are updated to the Mog Station.
2014 Moogle Attire Statement:
*Does NOT specifically state "exclusive" other than a line leading many players to interpret meaning to be exclusive.
2014 ARR Pre-Order Bonus Items Statement:
*Stated "Limited" as well as many vendors (gamestop, bestbuy, amazon) used this as a sell point as Exclusive PreOrder bonuses.
2016 Fanfest Vegas Stream Statement:
*It specifically does state "exclusive" on the FF-X items- At least for the Minions. I guess the attire could be up in the air but it does use "items" being plural at the top may mean otherwise. I'd be curious to see if these reappear in 2 years since the fine print actually states "exclusive" this time around.
Going by the above's fine print technically I could see why the Moogle Attire was added, (I don't agree with this because of the way this item was talked up and hyped up again by staff during during the actual 2014 Fanfest event at the Rio).
I'm almost certain we saw the color change on the Moogle Cap specifically because there could be potential legal actions taken against 3rd party vendors who ultimately used the Caitsith Minion and the Moogle Cap as "exclusive" selling points for consumers to put in a preorder bonus with them. (Someone who bought the game could technically go back to the store that claimed these items were exclusive at the time and receive a refund for the game/preorder. Ultimately the Vendor would be at fault and could of course contact SE but would probably open a whole other can of worms to be dealt with legally.
It seemed like there was a quite a lot of requests at least on the NA side for the Moogle Cap item though regardless- I get it people start the game later want access to cute items. I'm sure their workaround was the pom reskin so those who received the Bonus Pre Early Limited items could keep their originality of the item.
Because of this, certain items that were advertised as such (or similar to the Moogle Cap / Caitsith Minion) which probably include any Game Collector item that stores advertise, (Behemoth Mount, Legacy Chocobo, Onion Helm, Garlean Goggles, Asuran Armbands) probably will only make their way into the Mog Station as a re skin- which I think for the most part people would be accepting of.
Who really knows though ¯\_(ツ)_/¯ this is my going theory at least.