They already did those for a special event. Well, XIII anyway for Snow. They have run the Lightning event 3 times so far, both the Snow and Lightning hair became available after doing the event. They have said it will not return but there's always a possibility. but that would then mean those special events would have been pointless doing.
I hope you know they have Easter, Valentine and Halloween items for the quests on the Mog store.... So why cant they put it up for an event they don't plan on making anymore. they are events that happen every year. the lightening 1 is a special event not a seasonal.
Sorry to say, my main is a female now. And I'm not feeling the selections! I need Rikkus hairstyle from FFX2. Since I named my toon Rikku Albhed .