In D&D, you have a DM, some players going through the adventure, and unknown encounters before you. I think that's rather odd, because most games and theater forms don't include either of these elements.
In a game, you know the game ahead of you. The rules don't change. You know what to expect.
With a play or a TV show, you may watch something novel, but many people like watching their favorite plays and movies over and over again. How many theater companies have done Hamlet or MacBeth? Still, after all these years, people go back to see that. Even more importantly, the actors know the play that they are about to perform in and rehearse and develop their characters with full knowledge of their impending doom.
So, if we want D&D to act as a theatrical form, why does the adventure remain a secret? The game side will always remain the game side. The rules don't change. The fights will still be challenging. The drama side can only be enhanced by knowing about the adventure ahead. Why not change the paradigm?
What I would like to do, sometime in my busy schedule, is to run a game where the players brainstorm with me to create an adventure. The players also brainstorm how their characters can interact, and various ways that they can improv during the adventure. I then run that adventure, administering the rules, while the players play to the adventure before them.
To me, that sounds like a wonderful game.