The find the idea that turbulence caused the crash scarier than terrorism. I recently have made several trips to Reno, NV which (according to residents) is the second most turbulent airport in the country. Last time I flew there the plane I was on (an Airbus A-300) experienced turbulence that was so rough that even air traveling vetrans were made sick. It was a real white knuckler. The crew seemed to find it routine, however, and the pilot barely commented on it after the plane was safely on the ground. I would guess that turbulence is not generally something that cause planes to come apart in mid-air.
You're totally correct that people would be far more scared if this was caused by turbulence....and that goes for the people in Queens, too....they have thousands of planes overhead every week..if it was Bin Laden, they can think about specific government efforts to eliminate him, look for a concrete solution in the future..if it's turbulence...it's always going to be something that can happen.
And when planes crash due to non-terrorist causes, it's usually due to a rare combination of events/failures often combined with some pilot error, too. That's why crashes or so rare...you need a rare combo of maintenance/inspection failures, or precise weather conditions, or a sequence of unusual pilot errors, or all three in combination.
But, this gives every conspiracy loon fodder for almost any crash....when the cause isn't terrorism, it's still usually a rare and unusual combo of events that makes people suspicious.