Software vendors make money selling their software. But you can't sell somebody the same version of the OS that they already have, unless you are Apple, then you just move the OS version up by 1/10th and the iFanboys will buy it. Windows 7 came about because XP had nearly reached the saturation point. Windows 8 because 7 isn't giving people a reason to leave XP. The big problem is we really hit the level of maximum usability in your UI and now you have to make changes for the sake of making it different, so they rip out the functionality and claim it's "improving the experience".
No thanks, I'll stick with what I have for as long as I can and hope that sanity returns when I eventually have no choice and have to update because of hardware issues.