This is largely an entrepreneurial site, so tell me: if you tried a concept and it failed, then you repackaged and tried again with another failure (redo this step multiple times as necessary), then saw someone else alter your concept and have enormous success would you:
a) Learn from them and make a product that competes in that space or
b) Try your same multiple-times-failed strategy again?
If you're MS it seems option b is the right answer. PC in tablet form, take... what, 5?
In what why is this the same strategy? Windows 8 has a completely new API. Win32, which has been around since the early 90s is gone. The new API doesn't even have the concept of overlapping windows. WinRT talks directly to the kernel. In that respect, Windows 8 is as much of a "new thing" as the iPad or Android or any other tablet OS.
The only thing they've chosen to do differently is in marketing. The other tablet OSes are marketed as completely new things and Microsoft is marketing it as an iteration on an old thing.
Is it going to be the same thing they sell on the desktop? That's the goal, right? So it's PC in tablet form. Just like every time they've tried it before.
a) Learn from them and make a product that competes in that space or
b) Try your same multiple-times-failed strategy again?
If you're MS it seems option b is the right answer. PC in tablet form, take... what, 5?