Lightning and Snow were just supposed to be fun...and an ad for Lightning Returns. I understand that while the event is happening in game, the costumes will be all over, and that even afterwards, you might occasionally see a Snow Roegadyn or Lightning Lalafell hanging out with a Reindeer Miqo'te. But seriously, it's just for fun. The event won't be in the game forever, and just like the holiday events, you can avoid them/choose not to participate or play if it bugs you...

Example:
Every summer of FFXI/FFXIV I have played with the volume off during their summer events, because I hate the event music. But the event passes, life moves on. And while it affects my enjoyment of the game a little, it brings joy to other gamers. I can ignore it for a few weeks/take a couple weeks off to catch up on some console games and everyone is happy. My personal preferences and likes aren't more important than theirs. And the event is a fun break for many people.

The same is true of the Snow/Lightning event. It doesn't have to fit...it's just for fun. It doesn't have to please everyone. (I don't even know if I'll do it). But Lightning won't be in game forever (unlike many of the 'staple' npcs/characters people are using to prove their points in this disscusion), and once she's gone and the event is past, the gear will loose it's popularity once the next thing is out. (New Primal, Dungeon, Seasonal Event etc.).

So if you don't like it, don't participate....if it really really bothers you, don't play during the event. Come back when it's over. It'll be okay. A lalafell running around with a vanity bow and gear isn't going to break your gameplay...or even your immersion. (The gear isn't THAT different from what is already in game)