They've been compared to traffic cops. But traffic cops are enforcing the law, and music doesn't have laws, only rules. You can't get into an orchestra without being a good musician in the first place. You have to be able to read music fluently, and practice your part over and over. Musicians aren't just looking at the music, they're also listening to the other performers. I can't even imagine that conductors are like movie directors, who arrange the sets, the lighting, the way the actors interact, and practically everything. So why are they important? Are most of them even composers?