Since much of the story is told from the perspective of Pip, reflecting back on his childhood, these fairy tale elements add to the sense of Pip as a young, innocent child in the begin of the novel. The book progresses through Pip's years in the world, becoming self-centered and self-serving, and cycles back to his knowledge that money and happiness are not the same. By bringing in fairy tale elements, Dickens is able to make this transition more clear. It also adds elements of suspense and mystery, which help move the plot along through places that otherwise might drag.