There are several ways of viewing the matter of Form vs function. The question for balancing creativity versus composition applies in many fields including writing fiction. To some form is all important; aesthetics are what matter. For others function is the essential purpose of building a story, building or whatever.
Solzhenitsyn's 'The Seventh Circle's fulfilled a purpose with expository writing through fiction of explaining life in the gulag for intellectuals. A philosopher writing science fiction would have a purpose- the function being invaluable and the form secondary. Plato's book The Republic, is logical analysis going so far in describing the realm of forms that it may be regard as science fiction twenty-three hundred years before Mary Shelly wrote Frankenstein. Like Sartre, Plato's prose- the syntagmatic axis, were flawless.
Without function and purpose that is interesting and edifying a novel is like an electric car without a battery. The paradigmatic axis need be built into a story as the chassis. One may produce beautiful meaningless verbiage without it. Build the story with a purpose and use the editing features described others of rough draft and subsequent stages of refinement. It is quite difficult to infuse purpose into a story with editing.