This sort of argument can be brought to the next level by simply saying you shouldn't be out on a road with your 20lb bike and open face styrofoam helmet shoulder to shoulder with 2 ton rolling chunks of metal piloted by people who must only pass a joke of a licensing process.... if you give a crap about those in your life.

It's not that simple.

Also, comparing motorcycling to bicycling is an inviting concept but not nearly as logical as it might seem. The equipment and physics involved are actually quite different. At least too different for use in arguing the effectiveness of bicycle helmets or making ones own choice to wear one.