The running length of a show doesn't nessecarily detract ticketbuyers. Cast-in-point: I'LL EAT YOU LAST: A CHAT WITH SUE MENGERS.
MURDER BALLAD could work on Broadway if they setup the stage with the bar, and did on-stage seating. You would then have two ways to experience the show: 1) being on stage in the bar, or 2) observing from the auditorium. This would be a hideously horrible decision. The show wouldn't have a prayer on Broadway.
"The Spectacle has, indeed, an emotional attraction of its own, but, of all the parts, it is the least artistic, and connected least with the art of poetry. For the power of Tragedy, we may be sure, is felt even apart from representation and actors. Besides, the production of spectacular effects depends more on the art of the stage machinist than on that of the poet."
--Aristotle