Yesterday I did the Custom Delivery quest for Kurenai where she and Hisui wore the same kimonos that Tataru wears on the picture you linked. Seems like they even are dyeable (and they seem to dye nicely too). The Hingan housing NPCs and other NPCs in the game also wear different ones and similar eastern themed clothing. And we can't have any of them...

I get that it probably looks weird on some classes like Monk because the kimonos are very tight around the legs. But we get so many clothes and hairstyles that clip into everything that it just doesn't matter anymore. It's my choice if I would want to wear a kimono on Monk even though it would look stupid with the animations.