Helmets aren't totally protective, obviously; if you're going fast enough, they won't protect the contents of your skull too well anyway, and many skiers also note that helmets decrease peripheral vision and have the potential to create false senses of security that lead to potentially dangerous accelerations. All of which is true, but as this Time article points out:
Those claims may well have some truth, but seat belts too may create a false sense of security, yet few people argue the wisdom of wearing them. Helmets may not provide the same level of protection as a seat belt, but in some cases, even inconsistent protection may make all the difference.
All I'm saying is that when you decline a helmet, you decline a safety tool. Richardson should have been better persuaded to wear one, both by those around her as well as by her internal sense of reason. I hope that what happened to Richardson at least serves as both a warning and a reminder to others that, regardless of how dorky it looks, you should always wear a helmet--even if you're just riding your BMX to the library or hopping on a skateboard in Union Square.