As someone who lived in Japan, this isn't about theme park culture, it's more about popular culture in general and how much of a grip it has in that country, even more so than in America. It's very much influenced by both Asian and American popular culture, especially for younger people. None of this is surprising and been happening for a very long time.
And its not a big deal. As someone said, it's just marketing. Everyone will look at this stuff differently. Middle age people still buy stuffed Mickey dolls that they keep for themselves. Most people not into theme parks or only looks at them for kids would suggest that's going too far too. And yet it's been happening for decades now.