There are times as a writer where I take in other people's opinions. The most obvious example is my writers group. I submit pieces and they make notes and hand them back. In return, I do the same for them. And it's rather satisfying to suggest to other people what they need to do to correct their story. (They should always, always listen to me.)
However, what they do with what I say is entirely up to them. After all, it's their name on the title page. My name may or may not show up in the acknowledgements page. (Thanks, Fleur!)
And I can take or leave their suggestions without a committee or an audience. I nod, say thanks, and move on. Every adjustment I make is my own and I'm the only one who has to answer for it.
Theatre works a little differently. Theatre is collaborative. There is more than one voice going on at any given time: playwright, director, actor, etc. Collaboration has inherent constraints that aren't present when you're your own boss.
For example, tonight at rehearsal for Marat/Sade, I was reminded of just how different writing (solo) and acting (collaborating) are. There was a section where blocking was giving some difficulty in which Sade, who is the center man (after all, the play is his big Fuck You to the Man), was getting upstaged by some delightfully raucous musicians. This was understandably annoying to Sade, whose speech is kind of important to the point of the whole play.
Being in the ensemble, I'm basically opposite the audience and saw that a small adjustment in blocking would keep Sade center man, instead of being brushed to the corner. I made the suggestion to the director -- during the break -- and he gave me a hug, said thank you, and then passed the suggestion on to Sade.
Unfortunately, the set being the chaotic place it is, there was really no way to take the time to communicate the change in the time allotted. So there was a stumbling moment while director and actor went back and forth in front of everyone. No one got loud, but you could tell that maybe the better time to discuss this would be later. Which is basically what it boiled down to.
Throughout the whole exchange, I cannot tell you how hard it was to stay quiet. I can see how it will work and if I had two seconds I could get the picture across. But, in the end, I'm the chorus girl. I'm not the director, or Sade, and their responsibilities aren't mine. I'm there to fill one slot of the story. I'm not in charge of the whole story.
And, while other writers can keep or dismiss my suggestions at their leisure (to their peril), theatre means you take the director's note and adjust accordingly -- because someone has to be in charge of this chaos. His tools are actors and sets and scripts. All of those things have opinions of their own. By jumping in further and insisting on my change (which may or may not work, after all) I would just be adding to the chaos. So, with great restraint, I kept my mouth shut. They'll sort it out.