A recent Q&A with Yoshida included a question about Yotsuyu's dress being made available, and he said it was (unlikely? / not possible?) because it hadn't been designed for full player movement.

I'm guessing the full-length kimono worn by NPCs might have the same issue - it's built for characters standing still or walking slowly, but running or battle stances might break the 'skirt' or stretch it bizarrely.

I'm not expecting any longer flowing hairstyles like Ysayle or Yotsuyu. It's possible the game can cope with displaying the one NPC but might have a meltdown if you potentially had a crowd of players all using it (and needing wind movement calculated) at once.