Will Wright expressed some regret that Spore turned out to be less simulation than toybox. His original vision was less cutesy and more scientifically accurate (it’s been accused of covertly approving of intelligent design). Well, looks like somebody didn’t get the memo!
These cubic planets are allegedly the result of a new patch (1.02 if you must know), and are possibly intended to pacify the outcry over Spore’s DRM, lacking gameplay, and the inevitable avalanche of expansions. My guess is they just couldn’t figure out a way to charge for this.