That's because people generally don't like their stars to come out from behind the camera. They go to the movies or watch TV to be entertained, not to be lectured to by someone earning absurd amounts of money and living in a virtual la-la land. It's insulting to the common mans' sense.
Absolutely! "Shut Up and Sing" is a great book title, and excellent advice!;)
They aren't smart people. They only play them on TV. And I seriously doubt any of them slept in a Holiday inn last night.