@LateForLunch
The golden ratio.
A different functional morphlogy applies, not so much determined by atmospheric sleekness, but a balance of masses around a center with the appropriate drive(s) and, when needed, landing gear.
So much of our eye is developed in a set of circumstances where the beauty of form is determined by ability to function in liquid or air, or to move across landscapes at 1G. Even the Enterprise of Star Trek has its propulsion units on one 'side' of its mass (ship relative 'up'), which, while it might appeal to those who cut their teeth on naval vessels who would see the saucer section as a planing hull or airfoil (which would only be mass to push in space, and contribute nothing to maintaining the attitude of the ship) would without other factors cartwheel through the aether until encountering some other object or dismantling itself through internal stresses generated by spin.
The Borg cube is a more practical ship, and the Deathstar of Star Wars, even more practical, because corners are tougher to maintain internal homeostasis in than a cubic shape.
Change the rules, and the concept of beauty could change with them (more dense atmosphere, higher/lower gravitational environment, the absence of planetary surfaces, liquids, or even atmosphere). To our dirtbound eyes one form is beauty, but would a different sense of beauty be derived by a different circumstance? Would we become attracted more by different functions than those of hull lines designed for a water world?
And by then, with the idea that ships in space (like X-wing fighters in Star Wars) might function differently there (rather than maneuver like aircraft in atmosphere), our sensibilities might find the squat ugliness of a cylindrical or spherical craft rotating on an axis and changing vectors to be far preferable to the sweeping maneuvers of a flying bird with wings or a craft that didn't need them--and in popular depiction, ships in space would behave more like, well, ships in space as opposed to fighter planes in atmosphere.
