I don't understand what Microsoft is playing at in recent years. Their business is based on selling OEM software since, inevitably, we all have one or another original Windows license from buying a laptop. That is, as far as operating systems are concerned, they have the market share secured. So I don't understand the limitations they put on their software like IE or DX that only work on the most recent versions of Windows. With that, they're not going to sell new Windows and they're forcing users to stop using IE.
As for DX, there are already quite a few developers who have given their opinion on Windows 8 (Increasing criticism from video game developers against Windows 8). And with Steam for Linux around the corner, increasingly well-founded rumors that Valve is planning a console based on Linux, DirectX doesn't have a very bright future ahead (although it won't sink, it can't expect to improve its market share).
And now they go and radically change the graphical interface of their operating system without bringing anything interesting to non-touch machines. In other words, one of the big assets that MS had with Windows was that everyone, after almost 20 years of tradition, had gotten used to the start button and they come and remove it.
The truth is that I don't understand it. Backward compatibility and the continuity of graphical elements are the things that make people keep using something. If you take something away from that, you increase the probability that someone will say "now is the time to change".
I suppose that with IE 10 they saw that it's useless not to give backward compatibility, but they sure can't give a convincing argument about why it can't be installed on Windows XP, apart from the tired excuse of "it's for security".