Try blaming the fact that the current sales reflect the number of people that actually WORK at a computer. If you spend your day with Word, Excel, and Project open, you are probably going to want a desktop and two large screens (like the one I'm typing this on).
On the other hand, if most of your computer use is fundamentally PLAY, why not go to a tablet or even a smart phone. Nobody needs two 23” monitors to check what some imbecile celebrity just tweeted.
Yep blame the tablet which also runs windows 8. So it’s not windows that’s over it’s the desktop PC that is over.