Why you should ride a motorcycle without a helmet?

Because you have this strong urge to volunteer as an organ donor...

No, seriously - IMO you should never ride w/o a helmet.

For what they cost, they improve your chances of coming through an accident or a fall alive a tremendous amount, which seems like a good thing to me.

Some people think that helmets are "uncool", uncomfortable or that they're so skilled riders that they don't need them, or that it should be their choice to take that risk.

Me, I'd take the protection ahead of the style points any day. Alive and nerdy seems better than dead cool.