It is important to remember that literary fiction is an art form. Symbolism is a tool that helps a writer to establish their style; handled well, it adds much to a work's aesthetic value. F. Scott Fitzgerald is famed not only for his lyrical prose, but also for his skill in weaving symbolic motifs throughout his work, such as in The Great Gatsby.
Fitzgerald uses color symbolism to great effect in the novel. White is Daisy's signature color; it surrounds her in her home, her car when Gatsby first meets her, and her clothing. It is used ironically to suggest that she is far from what the color usually symbolizes: purity or innocence. Green is associated with Gatsby: the jersey he wears as a young man working the Great Lakes, the leather interior of his opulent Rolls Royce convertible, and the color of the light at the end of his beloved's dock and the symbol for his dream.
The names that Fitzgerald chose for his characters also have symbolic elements. Daisies are winsome flowers with white petals whereas myrtle is a hardy, evergreen shrub, and it seems likely that the contrast is meant to be somewhat humorous. Cars of the 1920s included a Jordan and a Baker; one was sporty while the other was more conservative, as if to suggest a paradox within the character.
Symbolism in the hands of Fitzgerald becomes a writer's tool that adds style, deepens meaning, and aids in characterization.