Why is the director's role so important in a film? What are some of their responsibilities on a movie set?
The director is the chief creative force on the set of a movie. They visualize, design and direct the conception and style of the film. While this mainly applies when shooting scenes, the director carries out and oversees other production jobs such as casting, editing of the screenplay, shot composition/selection and post-production.
The director's role is critical because they are responsible for painting the visual and audible image we watch from its original pages in the script. They are ultimately responsible for whether or not the film is successful creatively and commercially.
The director can even be responsible for writing the script if a dedicated screenwriter is not available or wanted.
Also, during post-production, directors that work closely with the editor/editing department through their technical and artistic process produce better results.
In conclusion, the director is working from the film's conception to its final cut. They must produce creative, commercial and financial results. They must work closely with each department to convey his vision and motivate the team. They must have an attention to detail, and the determination to succeed.