In light of the Qantas incident that involved its Airbus A330-300, I hope this will serve as a lesson to all to ALWAYS, ALWAYS wear seat belts whenever you are seated on an aircraft. You will never know when the plane will encounter extreme turbulence.
The Qantas Airbus suffered a drop of 650ft in a matter of 20 seconds, and as a result, many passengers who were not strapped in, suffered serious head injuries because they hit the aircraft ceiling. Some even suffered spinal injuries.
Remember, folks, flight safety is always there for a reason. Life matters more than inconvenience.