Because people like Japan. It has amazing cultural influence and is a direct competitor in almost genres of Western Media, which in turn makes people both see there are other options and reject the narratives pushed by said Western Medias.

I don't think its the immigration thing as much as it is the fact that weebs aren't a small nor quiet group, and are causing a lot of problems for the "plan" as it were by simply realizing you don't have to cooomsoom the slop in front of you only.