no, thats not it at all.
they know they're designs are good, but the thing that keeps OS X on them is that it drives sales. period. by licensing out OS X people won't buy macs. remember that this is a mac centric site, so of course a lot of people here would still buy macs, but for most people, they want the cheapest machine to run the software, and that means moving away from apple's offerings. apple is both a software and hardware company, its about a packaged system. and lets not forget the software issues that would arise from trying to support every possible configuration.