Brookhouse,
Ever had the delight of feeling 3000 PSI hydraulic pressure stopping the aircraft within an eyeblink? Even with all our straps secured on the flightdeck we still see the instrument panel from up close. Even more than we are comfortalbe with.
When FULL brake pressure is applied the aircraft will stop in a split second and people not secured in their seat will pay the flight deck door or the bulkhead a visit.
If an airline allows people to stand up before the aircraft comes to a complete stop and there is a need for full brake pressure to be apllied then the airline is liable for any injuries.
Depending on aircraft type you are still sitting on roughly 3 to 6 tons of fuel when you arrive at the gate. As people allready mentioned engines are still runnig and there is a risk of fire. Fuel and fire don't go together that well.
So that it what you are protected from.
Normally we have a listen out for PA's telling people to strap back in. A light tap on the brakes will normally help as well and people are eager to get back in thier seat.