I very interesting question, it made me think of movies and how some spoon feed the audience everything and nothing is left to the imagination.
So at first I thought no, because when I read a novel and read the authors descriptions, I want paint my own picture of the characters, surrounds, story etc based on how well the author writes and how well I use my imagination.
But then I thought it depends on the what the novel is about.
When I read science fantasy books they often have great artwork on the cover, maps and other artwork/drafting pieces which can be great reference material when reading through the story plus they can set the mood which may help the author in the telling of the story.
Now I'm thinking that pictures in novel type books maybe a great option. Oh...aren't they comics :))