Kim Kardashian West's kimono underwear appears to be a misnomer based on cultural misunderstanding and lack of knowledge. It may that be Ms. West wanted to use the word "kimono" as it has nice and charming connotations.
In the Japanese cultural tradition, "kimono" has a venerable and respected standing, a point not necessarily understood outside Japan. As "sushi" has come to be varied both in presentation and ingredients as it has spread all over the world, "kimono" might be in a process of evolution or degeneration as a meme.
A fundamental reason for this "kimono-gate" might be that in the English speaking societies, "kimono" has come to signify a "relax wear" worn in the privacy of one's home, in a way quite different from what "kimono" meant in its mother country of Japan.
It is hoped that this "kimono-gate" would kickstart a meaningful conversation of what "kimono" meant originally in Japan and how it has come to be accepted in the world in somewhat loose but creative or degenerate ways.