If I were to guess, Japan has a huge cultural presence in the west via comics, cartoons, and video-games. It is also "good weird." And historically it had a legendary reputation for electronics. That is a lot of western mindshare, especially amongst nerds. Chinas historic reputation is cheap crap and oppression. It has almost zero cultural presence in the west. I suspect between kpop and Korean dramas, westerners consume more Korean than Chinese media.