Logically speaking, I don't understand how this would work. You're sitting on a stool when the plane takes off, you're going to call backwards and onto the floor of the plane. You can't expect someone to hold onto a bar during something like that, like you can with trains or buses. And don't even think about holding onto that during any sort of plane turbulence. You're all going to fall into each other.
What if there was a thin wall that you leaned against during takeoff, with a half seat attached to it? Then on landings you turned and faced the back of the plane and leaned on the half-seat facing the back of the plane?