Forcing change, the horror
re: no boot to desktop.
It may be it's an OEM demand, not (just) a Microsoft requirement. They all want to be able to spend another $10 per system to ship with touch enabled screens. They don't want (can't afford to, will go out of business if they have) to compete with an OEM whose customers won't be asking for one (because the urge to touch metro is so natural, once it's in view). Similar to the "how do we move the industry forward?" issue in terms of peripherals have happened over-and-over again in the past. i.e. none will take the risk unless all have to take the risk.
It could well be that if they (the PC industry) does not force the change to (high quality) touch-enabled screens in all settings (all screens, not just laptops and tablets), they (the entire PC industry) will fail (ref: "the PC is dead" articles). And yet, as is being argued here, if they do force the move to touch, maybe they will fail as well at of user confusion, revulsion, reluctance to change.
It'll be interesting to see how this plays out. My guess is the OEMs are desperate to see hardware turn over again (since that's the only way they make money - unlike their AAPL competitor), and touch screens are certainly one mechanism to separate the "new and sexy" from the "old and busted."