Having played the game at the creatures phase, I've noticed that there is a definite efficient pathway to maximize your creature's use of DNA points. However, most of the player-generated creatures are just made to look neat or silly, and waste DNA on extra appendages that don't actually improve your combat/social statistics. However in reality, we see that animals that waste energy on useless appendages get eaten by more efficient animals. Essentially, Spore shows that an omnipotent agent (the player) isn't going to try very hard to design the best animals, simply because it's more fun to make something silly or artistic.

I suppose that could explain all those silly looking creatures that died out millions of years ago. Bottom line, I don't think this game really advocates either chain of thought, simply because it's a GAME of experimentation. The random chance comes from building creatures and seeing if they will survive with this or that, not that different from rolling dice. Sounds like a fun game, but I sadly don't have hours to devote to such a thing. All that time gets sucked up by Slate.