One wonders whether, as an increasing percentage of bookings are made on the internet, we're not approaching an age in which passengers are required to inform basic data like height and weight. LoCos might allocate seating on that basis, which might mean I (at 6'4") pay more but get a greater seat pitch than my wife (5'4") who would have to sit in a different "zone".
I do remember sitting facing back on the Vanguard, not on the Trident. During takeoff it helped to have the belt fairly tight but during the flight, no different. Landing, well, if the imagination rambled to a fast decelration scenario, one might want a helmet.