No More B/C Plot Lines And Fewer Characters?

I'm a writer/director working in Hollywood and am so sick and tired of the bean counters dictating cast and story requirements, that I've decided to go back to my musical theater roots. In the process of writing my musical, a Broadway writer recently told me that because attendance has fallen in recent years, single plot line with limited characters are the new requirement. I've written mostly ensemble films which, to me, feel more true to life but was sharply told to get rid of the B/C story and characters. Can anyone please offer me their learned opinion?