Actually wasn't jpop gaining traction 10-15 years ago? Somehow, in the US, it seems to have fallen by the wayside in favor of kpop
It was, to the point where people like Gackt was kind of a known name amongst anime and gaming fans.
I personally think part of the issue with J-Pop was that a lot of music felt like it is being made to fit anime specifically. When I think of J-pop, I think of songs like these (and these are all recent):
Nothing wrong with these songs, and some are even catchy and cute, but at the same time you could hear it perfectly fit an anime outro or intro, and some of them feel a bit safe in that J-pop/J-rock way.
K-pop didn't quite feel this way. Instead it felt like they would try to match the highest highs of western pop and break that worldwide barrier, to which they managed to succeed with a few groups, example:
I always find it to be a breath of fresh air with J-pop when an artist goes outside of the usual J-pop comfort zone, as this song blew up with over 500m listens:
In the end though I think that there is an issue with all music industries worldwide and they are all extremely exploitative towards musicians and
especially boy bands/girl bands. Most people don't have any empathy for these people/artists because they simply see the fame and think 'what could be better?' but we've seen and read too many screwed up stories to know that it is never that cut and dry.