MS is a victim of their own success. The success of the Xbox360 means that game developers target those system specs. What that also means is that if your PC exceeds those specs there is no reason to upgrade at all. I'm on a machine that was built in 2007. It has a quad core CPU and 6GB of RAM. The video card was replaced in 2010, and it still plays everything I throw at it with no problems.
There is simply no reason to upgrade. Why move to Windows 8, when 7 does everything I need it to? I don't want the Metro UI, so Win8 would be a step back.