Probably because the stuff in the Apple OS is not so tightly integrated with the OS. I.E. you don't need to use the OS X environment to use the OS. You can use KDE or GNOME if you like, heck you can even have a choice of file systems. Windows, on the other hand locks you into one file system, one operating environment, etc. Very little chance for innovation there, IMO.
if they dont want windows dont buy it.