Anecdotal stories about "the dangers of seatbelt use" are unhelpful.
Side-impacts by other cars are not particularly common. Today, it's SUV roll-overs and frontal impacts where seatbelts really shine.
Should the FAA should revise its seatbelt usage on aircraft? Where are this forum's airplane pilots on this, anyway?
With military, commercial, and General Aviation pilots in my family, there
IS no seatbelt issue.
BTW: Your insurance company probably sponsors this nation's many school-touring "Convincer" exhibits—a photo of one example, below: