Jensen Harris was involved in the design features of Windows 8 and he recently presented the story at UX Week.
He highlights Microsoft's core belief that if you give people enough good reasons, they will accept change (regardless of how radical it is). Let us not forgot that Microsoft has lead computing change over the last 3 decades :
- moving from DOS to Windows 3.1
- moving from Windows 3.1 to windows 95
- Moving from Windows 95 to Windows 8
Sure there were evolutionary changes in between but these represent the really big paradigm shift points. During each of this changes, a faction of their users complained and another group embraced the change. Eventually everyone understood the benefits of the new model and it became the standard.
If you have any interest in Windows 8, this video is interesting to watch