I would fix other people's lines if they asked me on occasion. The hard part of writing is the architecture of it, getting the story and structuring it. Not the tweaking of lines.
But obviously as television began, it so undercut movies that he was trying to think of a way to combine seeing these special things, and the fact that people were just captivated by the magic box.
If you already have a piece of music ingrained in your body, why would you not play it?