Yeesh, some people are wigging out right here in this thread. God knows what they'd be like in an emergency.
The article mentions people who were "thrown from their seats" by the turbulence. This is why I always wear my seatbelt, even when the fasten seatbelt sign is off. I really don't find it uncomfortable at all, and I'd rather experience the -1 in utility by wearing the seatbelt rather than the -1000000 utility I'd be at if my head smashed through the ceiling. I don't understand why so many other people are so anxious to unbuckle as soon as the sign is off (of course, excepting times when one needs to get up, I'm not suggesting anything that extreme).