The New Years even in NYC had some korean or jap boy group, this very year. I skipped through the channel too fast to see what was up. K-pop trying to go mainstream in US?
... confirmed, it was that BTS k-pop band from Korea.
This madness goes way back to the British Invasion times, when producers have discovered that en emasculated boy band with stupid simple chord songs can drive stupid girls wild. Unlike the Beatles, there were other American bands that were 100% manufactured together with that fashion making come back about wearing ball crunching tight, short pants.
It seems like this fashion comes and goes and in different iterations. In the 90s, there was a Russian/Soviet boy band with a falcetto lead singer that took country by storm. The manager was x-con who had at its peak (this was time before mass internet) had up to 60 (sixty) look-alike bands touring and singing to a recording. All band members were literally from orphanages. I think that some of that popularity was due to punk rebellion of the old music scene saturated with party approved, wholesome music about love for Lenin and motherland, while people just wanted to fuck.
In terms of emasculation and infantilizing boy/girl asian groups, it's also an interesting aspect. There is quiet an "old" Ukrainian trio, girl group that has been going for a while, with singers periodically replaced every few years, VIA Gra (Vocal Instrumental Ansamble "Game") that pronounces as Viagra. Again, 100% manufactured group with "singers" setup as male eye candy in skimpiest of outfits and oversexualized music videos. Kind of like Spice Girls, you got blonde/brunette/shaten, short/long hair personalities, whatever you are into there is something for you kind-of buffet.
The key difference is that "girls" while in the 18-20 range, are emphasized to be fully developed in all aspects, and this is in contrast to these Asian groups. So compare this:
to your typical k-pop or j-pop band and see if this somehow reflects on society and stan phenomenon. I don't think that there is such thing in Russia either. I get that to an American they may seem too skinny, but in the old country a lot of girls tend to be in athletic/skinny category. At least there is no way you can mistake these band members for middle school girls.