Lucy and Jules may have seemed extraneous to the story, but they gave Puzo a chance to show that Michael was generous to people with some connection to the Family. Michael didn't just let Lucy just fade away after Sonny got whacked, he gave her a job. Jules helps Michael (and Johnny), and provides Michael with a nice prop to give a speech about loyalty. Nino gives Puzo a chance to show off what he learned about Hollywood, which I liked less, and which was out of control in "The Last Don."