@Rick, one of the reasons people seem to feel more pressure to keep up with Micorsoft updates is that eventually new software will emerge that simply will not run on their computer because the OS isn't supported. To liken this to your washing machine analogy, I can place a new pair of jeans in a 50 year old washer and they will get washed.
Another concern is reduced productivity, for this point I will refer to your GM analogy and borrow something I have heard several times lately. If GM were to launch a new car with a Joystick to replace the Steering Wheel, and add buttons to the Joystick to replace the Brake and Gas. The new car would work, it would not require new roads to be built and some people would love driving them. However most drivers would find the new controls a hinderance to transportation.