You're making the case that Windows ME sucked, Vista sucked, 7 was good, and 8 sucks.
You're absolutely missing the bigger picture, which is this: nobody cares about operating systems anymore. Everyone, I think, finally gets that the function of the operating system is to get out of the way of the application that the user is running. iOS and Android are perfect examples of this. Everyone who argues about operating systems now talks about contextual menu this, flat button style that, driver update this, without realizing that the typical primary use of a computer these days-- desktop, laptop, tablet, whatever-- has nothing to do with the operating system and everything to do with HTML and JSON.
You talk about how a lot of people bought iPads thinking that it would fully replace their PC, and now they're disappointed. I would argue that, based upon the rate at which mobile web traffic is increasing, those people are anything but disappointed.
I have serious doubts that there will be a Windows 9. There will simply be no market for it. No kid today is asking their parents for a Windows Phone or a Surface. None. When those kids grow up, Microsoft will simply stop existing save for the Xbox.