I think this is the most important one on the list. Windows 7 is a solid, fairly usable OS. Windows 8 offers no compelling reason for anyone to upgrade from Windows 7, and anyone looking to upgrade from XP or Vista has likely already gone to Windows 7.
Someone upthread mentioned Mac/OS X -- for better or worse, Apple has decided to go with smaller, more frequent, and cheaper upgrades. That means fewer bells and whistles with each new version, giving the (correct, IMO) impression of incremental upgrades rather than anything to specifically crow about. It's quite possible to skip an upgrade or two and still be using most of the latest and greatest stuff (though I do need to do the Lion -> Mointain Lion update at some point to get full benefit of Mac/iPhone synchronization).
I can’t imagine business users being forced to use 8. Productivity would crash in a free fall.
I want the OS on my computer to be invisible, or as close to it as can be managed. When I plug up a peripheral, I want it to work. When I use an app, I expect it to be easy to find and use, and have an interface that doesn’t get in the way. I want the computer to not require a daily restart to avoid memory congestion, and I want either security or ease of using my own security. In short, the OS should do its job with a minimum of fuss and otherwise stay out of the way.
Basically I haven’t seen the need to change my OS since Windows XP Pro. Though I have a Windows 7 PC at the house, I find the system interface to be more trouble than it’s worth.