Many of the books/plays/folk tales that are deserving of being musicalized already have been so it's not such a huge thing for them to cast their eyes to Hollywood. As many other posters have stated there isn't a whole lot of original material out there.
Not long ago TCM aired the film version of the Matchmaker with Anthony Perkins. I think I actually enjoyed it more than "Hello, Dolly". I found it to have much more wit and charm.
And just because people have a different way of saying "look at me - I have talent" than they did 50 years ago doesn't mean they actually have less talent than anyone else. Sure, there are people from AI that I, personally, don't like but I don't think they're undeserving.
"All our dreams can come true -- if we have the courage to pursue them." -- Walt Disney
We must have different Gods. My God said "do to others what you would have them do to you". Your God seems to have said "My Way or the Highway".