I'm more interested in ideas themselves than details about how they're marketed. Plan 9 and its novelties are well known and published in detail. The authors of Linux, BSD, OSX, and NT are aware of Plan 9 and decided it wasn't worth imitating. What could be gained by wasting time lobbying to change their minds? They care only for what they and their customers want, and the average Joes that Microsoft and Apple sell operating systems to aren't exactly clamouring for them to be more like Plan 9. If you like an idea, then adopt it yourself. If not everyone shares your taste in operating system architecture, that's alright too.