I enjoy reading it. I learn from it. But that's not the usual way a program is used. Whereas novels and songs are made mainly to be appreciated, not run. The way you enjoy a novel is simply by looking at the words in it.
Software is functional.
Novels are not functional and this makes a difference. The freedom to modify programs and publish modified versions is vital. Whereas for novels, I don't think it's vital. There are some kinds of works of appreciation where the process of modification has a valuable result. It's complicated to determine what to say about the freedom to modify things like songs or poems.