Originally Posted by
the810
Problem is that unlike human, the bag can slip to the front when "strapped in" like this in case of a severe turbulence.
No, it can't, because the seatbelt is lopped through the handles. There is a few centimeters of margin max if the forces go back and forth.
What you describe can happen to the suitcases in the other picture above in the D and F seats. Nothing holds them "back". They are only held "down". Which is why at least I wouldn't feel comfortable with that kind of luggage being put on seats when secured in that way.