There are many who just refuse to watch a B and W film. They can’t relate to them as realistic.
And then there's "Schindler's List". I don't think the movie would work as well in color, because we associate that era with the black and white newsreels.
However, I think the real reason the movie-going millenials prefer today's films is because they are into vehicle chases, crashes, explosions, planets colliding, graphic murders and death scenes, the Capitol blowing up, planes colliding, zombies on the march, etc. etc. and so forth...and Hollywood is churning out just what they want to see.
Movie star-wise, Arnold Schwartzenegger is the new Humphrey Bogart and Lady GaGa is the new Ginger Rogers.
Leni
It's how kids are raised.