I have a feeling that books are a lot like people - they change as you age, so that some books that you hated in high school will strike you with the force of a revelation when you're older.
In terms of writing, I think what most fiction writers treasure more than anything is the feeling that they're living for the length of a book inside another person.
While writing, writers are living inside a character or characters, and when the book ekes into the world, writers are living inside the reader. That's more than connecting.
When I was small and easily wounded books were my carapace. If I were recalled to my hurts in the middle of a book they somehow mattered less. My corporeal life was slight the dazzling one in my head was what really mattered. Returning to books was coming home.