Intersting perspective. I have always thought it got really bad as a result of American Idol. That audience stood for every GD number. Since it was a mega-success (and presumably attracted an audience that included many who attend musical theatre), those viewers essentially became de-sensitized, and assumed standing was normal, as opposed to recognizing something truly great.
I can see your point, though. 'I paid so much to see this that I am going to love it, whether I actually do or not'.