Crumple zones, seat belts, and air bags are a far cry from setting hard limits on performance characteristics of the vehicle, even if those same requirements may have had a negligible impact on vehicle performance.
I guess the question is where the line is drawn between sensible and "nanny-state" regulation.
to me, the rule of thumb is: does this regulation encourage innovation, or curtail it? it isn't black or white, but i think it brings it into focus a bit more.