[hoc]

While I would agree in general, I once slipped on one of those overly steep carved-out kerbs in SF and broke my elbow... I guess if you hit a bad spot you might need a wheelchair afterwards (ok, but it really did hurt!)

So you have to do it right to keep the potential harm as low as possible and not forget about security in the face of rewarding improvements. And watch your step, of course.

Might also be applicable in the context of self-learning household robots and their potential to burn down that house :)