My helmet has saved me from pain, and that's good enough for me. Even a small tumble can knock your noggin into the pavement hard. I feel naked riding without one.

On the other hand, the evidence as to whether helmets make cyclists safer is debatable (there is a sticky on that, so I won't go into it here), so I wouldn't force other cyclists to wear one.

One non-safety advantage is that if you are in an accident, your word will likely have more value to the cop, insurance adjuster, etc. Much of the public (acurately or not) equates wearing a helmet with being a safe rider. I'm not saying that's right, just that it is.

Yes. As in driving while trapped in a steel cage.