One point that hasn't been made is inadvertent autobrake disconnection. With feet on thd floor, you're less likely to accidentally disconnect autobrakes,
That's true. With feet up one needs to use rudder with pressure on heels and keeping the ball of the feet lightly on the pedals. In case of AB malfunction it's very easy to slam both brakes without any delay. Also true that in case of reject AB provides instant symetrical braking.