There's only so many aesthetic permutations, and if the ones people choose are constrained somewhat by how these affect combat roles and proficiency, then some are less likely (sticking with a certain gun/armor/spaceship even though it's weak for example). So those are limiting factors on uniqueness of player character appearance. However, there might be some feature to make a more unique backstory for your Guardian. Even simply as a kind of character bio type thing that doesn't weigh in on gameplay (but could be secondary to things that do such as physiology / character class). That opens up more avenues for storytelling and role-playing, if only from a strictly imaginative direction. Then again, supposing, say you can choose your character's place of origin in the city and backstory, that could also affect how NPC's respond to you when you visit your character's "hometown" so to speak. Faction affiliations could tie into this as well.