I definitely agree that the movie is about Barbie so it makes sense that the Kens get sidelined.

But to my point, I think you're describing what I'm talking about. The Kens rubber band around between being the oppressed group in the gender reversed Barbie society, to being the cartoonish patriarchy that stands in so that Barbie can self actualize.

Actually as I type this out I guess you could interpret it as Ken then doing a cartoonish version of self-actualization with the funny song and dance after Barbie has the real emotional arc of the movie.