"Many people use their computers all day at work."
That is PRECISELY why MS shouldn't mess up the UI and the OS paradigm! We can easily put up with the aggravation of a completely different washing machine interface, because we don't use it day in day out like we do with computers.
On the other hand, it takes a lot of time an energy to get one's computer to work exactly the way one wants. Having a new UI and OS imposed upon you creates havoc for productivity and lots of frustrations. Personally, I have never fully recovered from switching from Windows 98 to Vista and that's after having found ways to run some programs in a virtual machine.