If you claim that you "never had to upgrade Windows to be able to install some other random app" you probably haven't used Windows much then. There are games that need explicit version or newer of DirectX. You can't even produce from the C or C++ sources the binary application that runs on any Windows XP with the latest Visual Studio (11). Any C/C++ application built with Visual Studio 2010 won't run on Windows 2000 or XP prior to SP3. We developers try to build the applications that run on as many targets as possible, but even MSFT doesn't support us enough for that, seeing the older versions as the competition to their newest "shiny thing." Which is not funny considering millions and millions of users still running Windows XP.
See the various opinions on MSFT intentionally removing the binary compatibility which already existed in their libraries here: