WHBM's point of debris flying in ones face is valid in the case of rareward facing seats. If I rember correctly, the passengers in forward facing seats need to be protected against facial injury by certification rules, requiring the backside top of the seat in front to have a cushion so facial impact in emergency landing conditions may be allieviated. That's the reason why seats must be in an upright postion, so that the cushion on the back is in the right postion relative to the face of the rear passenger.