That's because the things adults in western culture are most hooked on isn't their own imagination, but other, wealthy, attractive people and what they say. That's why there is always this push to make things look closer to reality, and why any kinds of animated works that were popular by themselves have this inevitable shift to the "real medium" of live action. They want to sell you on real people as brands, not silly cartoons or artists.

Whether that speaks to the power of the advertising machine or the lack of imagination in the people is a question left to the reader.