I think Microsoft really liked the Office Ribbon, and they really liked the overall reaction that people had to the Ribbon. So they expanded the Ribbon beyond o

I think Microsoft really liked the Office Ribbon, and they really liked the overall reaction that people had to the Ribbon. So they expanded the Ribbon beyond obscuring the menus of their Office suite, to obscuring the entire desktop/tablet. The only thing a tablet OS has to do is be obvious about how to use the tablet. If you're really good, your tablet OS will be so obvious that people who successfully use the OS won't be able to explain how to use it, because they never had to think about it. The only thing a desktop OS has to do is not break convention too terribly or suddenly without obvious benefit. They only thing the two types of OS have to do jointly is don't interfere with each other. They don't need to support each others' metaphors any more than a bicycle needs clip pedals that accept fins.