I think the popularity probably has to do with familiarity. People wanting a good first-time Broadway experience will often look for something familiar, something they've seen at the movies or on television, one of the things that makes Disney shows successful... people have an idea of what they are going to get for their money, which is quite a bit more than what they fork over for a movie...
It's like why people flood the chain restaurants and fast-foods, they know what to expect, even if it isn't gourmet.
Personally I like surprises when they turn out well, but I've been known to make comfort purchases too.
I say more power to 'em, especially if they get more people to take a taste of theatre.
Here's to Patti And Tina And Yoko, Aretha
And Nona And Nico And me