It has been speculated that MS has lost their backwards-compatibility religion, but you still see vestiges of it in their strategies.
Maybe they don't have the discipline to ditch Windows for tablets, but they certainly have the willingness to steal (borrow?) ideas from their competitors. Putting the OS from Windows Phone 7 on lower power hardware (à la iOS and the iPad) is clearly the right decision.
It honestly looks more like a problem with pride and less like a problem with discipline.
I think it has to do with neither pride nor discipline. It's all about business.
Microsoft won't make much money by breaking backwards compatibility; in fact, they'd lose billions if they did. Think of the hundreds of millions (if not billions) of business licenses they have sold. Business customers want their old apps to keep working. Yes, I'm talking about the same people who still use IE6. Whether you like them or not, these are the customers who purchase thousands of licenses each, and there are lots of them. Losing these customers could hurt Microsoft just as much as, if not much more than, losing tablet-toting consumers.
Of course, Microsoft doesn't want to lose either market, so they'll produce a version of Windows that has both complete backwards compatibility with existing Windows apps, and a fancy shell to appeal to tablet users.
Maybe they don't have the discipline to ditch Windows for tablets, but they certainly have the willingness to steal (borrow?) ideas from their competitors. Putting the OS from Windows Phone 7 on lower power hardware (à la iOS and the iPad) is clearly the right decision.
It honestly looks more like a problem with pride and less like a problem with discipline.