Spore isn't supposed to be a scientific simulation, it's a form of entertainment. Programmers tend to prefer their games to be strictly rule-based simulations, but that's not necessarily what the target audience want and it doesn't equate to good game design.

I'm not saying that Spore is perfect, just that it's very easy as a game developer to get carried away with stuff that you find cool, only to find there's no game there.

The irony is that Chris Hecker is pretty much the man who popularised (and evangelised) the use of simulated physics in games. Virtually all papers on inverse-kinematics in games reference his essays.