Is it so hard to imagine that in 5 years most people will have tablets that they dock into a larger monitor and use with gestures and dictation instead of mouse and keyboard?
Maybe for light work and consuming media (which is already what tablets are used for) but for heavyweight work a keyboard and mouse is going to be the interface of choice for a lot longer than 5 years. Do you think, for example, a Visual Studio developer is going to use gestures and dictation to write code, 5 years from now?
In any case, that's fine, that's why there's a tablet edition of Windows 8 - WinRT, and a separate phone-optimized version too. Having separate user interfaces optimized for different tasks is great. So why force the desktop edition to use the tablet interface? If they must bundle the tablet interface in with the desktop edition, why not make it optional, and just make the tablet interface the default on devices with a touchscreen?
To use a vehicular analogy: to keep up with the trend towards motorbike use and away from cars, Microsoft Automotive's latest model of car now has no steering wheel, pedals or seats. Instead it has handlebars, a throttle joystick, and forces you to lie in a prone position, but only when turning a corner.
I think I understand what they're trying to do by forcing the Metro launcher on desktop users, but I don't think they have fully grasped exactly what their bread-and-butter users think of that. It will hurt their reputation even more than the Vista debacle. It could even kill Metro altogether, and with it, Microsoft's plans for phones and tablets.