Why EXACTLY do we need our Seatbacks in the Full and Upright Positon?

I flew sitting in a back-ward facing seat several times in the military. The most memorable was the first time I flew on a COD mission in an S2F - this included a carrier launch and long flight to a NATO base. The cat shot was a real strange sensation and all our gear ended up in the tail of the aircraft - kinda scary to see all that stuff bouncing around back there.

As a completely disconnected aside, I wonder what the navigators in some aircraft experience - they sit facing the side of the aircraft!

the most important reason of all for having all the seats face forward:

How else can every passenger see the movie?