Call it Epic Theatre. Call it Alienation Effect. Bertolt Brecht's influence over 20th century theatre cannot be denied. And while there are countless ways of interpreting what Brecht did and what his intentions were, and even if you believe in it or not, he was on to something when he said "I am all for realistic acting and realistic theatre - but the reality of the situation is I am sitting in a theatre."
So think of that statement in relation to theatre's last innovative movement: Stanislavski's Realism that capitalized on suspension of disbelief to create a realistic world within the mise en scene of the theatre. Technology had finally advanced far enough were a realistic environment could be mimicked onstage well enough that you might start to believe that you were actually there.
He believed that a play should "present ideas and invite the audience to make judgements on them." That the audience should not simply be allowed to sit back and observe an entertainment, but participate in a didactic discussion or debate through the action of the play. His theatre becomes very self aware. The audience and actors alike are aware of the fact that the characters are being portrayed are not real. The performance style is more comparable to something you would find in a Vaudeville hall or fair ground than the Moscow Art theatre at the time.
To put it simply, Brecht accepted that theatre was theatre and embraced all of its conventions to make his point rather than trying to mask the device to recreate reality.
Now, take that idea and apply it to now. Stage technology has so increased that we can drop chandeliers and fly helicopters onstage, but yet the audience is still sitting in the theatre. On top of that, the film industry has reached its full potential being able to create realistic worlds that are realer than our own. The theatre just cannot compete with that. Audiences do not go to the theatre to see stunning recreations of their world when there is a film down the street that does that five times better and costs only $12.
So what do they go to see?
Live human interaction. Escapism. Something where they are asked to use their imagination to help tell the story.
Now does this represent everything Brecht had intended when he set out to develop the Epic Theatre? Probably not. But it does give theatre something that sets it apart from other media. European theatre has it a little better since it is not confined to realism in the same conservative way that most theatre in the U.S. is. Again, not to say that there is not experimental or abstract theatre here, it is simply not as prevalent in the mainstream.
When theatre is a business, as it is here, you always have to be accountable to your season ticket holders. It is much safer to make the easy pick that will be sure to put butts in the seats rather than taking a chance on something new. And while we are always looking over our shoulders for the next big thing, you have to be financially responsible about it too.