The 10 years line is kind of BS anyway. Yes XP has been around for 2 years but there have been 2 massive overhauls of security (2 services packs). Tons of Microsoft enhancements (Desktop Search for example) and even more tons of 3rd party apps that add functionality.

It's not necessarily an OSs job to innovate. The OS is supposed to make it easy to connect hardware to software and get the annoying hardware interaction stuff off the 3rd party programmers plate. So XP is fine because it's solid and allowed 3rd parties to innovate around it