We are too politically correct in trying to suppress the risks of injury during an unexpected event. Passengers should be told: "You are riding in a plane. It could unexpectedly and suddenly pull you downward with a force exceeding your body weight, or, in the event of an emergency landing, decelerate with a force exceeding 20 times your body weight - we'd like you to wear your seatbelt to hold you in." for your sake, and the safety of people around you.
Two years ago, I ripped a seatbelt right out of a plane, I have experience with being an occupant in a landing gone wrong.