First off, because it's not a first incarnation. Windows Mobile has been around since April 19, 2000; 11 years ago (ref: http://en.wikipedia.org/wiki/Windows_Mobile) and has been crippled inexplicably along the way--a lot this last time around--and hasn't made a lot of fans along the way. Windows Phone 7 is only the latest in a series of the same line and it's doing terribly compared to its competition who had FAR less time to make a mobile OS and grow them.