The idea of building a utopian city doesn't need to be a brand new thing for tech moguls to have a greater interest in creating them than other types of contemporary moguls.
Also, I don't think a company town is really the same thing as a utopian city. In my mind a "company town" is mainly an attempt to maximize exploitation of a set of workers, while a "utopian city" is built as a pure expression of some subset of someone's ideals, relatively unsullied by competing ideas, which usually aren't so crass as "maximal exploitation of the residents."