You have not stated anything like that either. You said that "Most users have an email program, calendar, contacts, music, maps, and the like, which all work just as well and are actually more efficient ..." But these things are not really *work*, they are "infotainment", if I can borrow a term from my car manual. Same goes for the live tiles. They blink some information, but it's not work, it's distraction. That's why I have not seen anyone attending a conference for example, who would be looking at them: that would be distracting not only to them, but to people who sit nearby.
If you are using your PC for "infotainment" - that is, browsing the web, listening to music, looking at photos - then perhaps this new interface is right for you. All I'm saying is that for real work it does not seem to bring any advantage, while there are some annoyances and distractions. Hence - why bother with it on a work computer?