A shortcut to NPC life
Without animate life, worlds feel barren. You could create three or four roles/animal types for each ecosystem, then give each role multiple skins. Maybe the giant spider on one world looks like an armored rhinoceros on another, even though they have the same behavior and stats. Maybe the trees on one world are really giant mushrooms, like ancient Earth used to have. Same object, different skin. This would allow planets to feel more varied and alive.