I haven't seen the play or the movie, but I know the importance of 'Ma Rainey's Black Bottom', of course. I would watch the movie simply to watch both Bozeman and Davis, but when I do see it I'll be watching for the flaws you describe here.

It's always difficult, as you say, to make a movie out of a play. Plays are, by default, intimate, while movies, by default, are sweeping.

Some, like "Who's Afraid of Virginia Woolf" or "Twelve Angry Men" can keep it on the stage because the drama is in the dialogue and it stays within the room, but Ma Rainey is meant to be bigger than life. The era they lived in demands attention.

That said, your description of the opening of the play vs the opening of the movie says it all. How the screenwriter and the director missed that obvious build-up to Ma Rainey's entrance is a head-scratcher, except this is Hollywood. More is less.

Beautiful writing, Petr. I thoroughly enjoy reading everything you write. And I always learn from it.