Do these guages work in all situations (including during a stall)? One of the (I think) significant problems on the flight deck of AF447 was that the aural stall warning was inhibited when the airspeed became too low for the aircraft to reliably calculate AOA. This lead to the confusing situation whereby the stall warning would sound every time the crew started to take appropriate corrective action and the airspeed came back up into the range where AOA could be calculated. The rest is history.
The AoA sensors worked correctly on AF447, the issue was with airspeed. The aircraft was so deeply stalled that the static port was angled in such a way that it was giving similar pressure readings as the pitot tube, not the static pressure. Because of this, airspeed was calculated at an incorrect and much lower value. The computers had a built in suppression of the stall warning at low airspeeds, so even though the AoA was extremely high, the stall warning did not chime.
Keep in mind the stall warning chimed for a minute or two until the aircraft was severely stalled. Had their been an AoA indicator in the cockpit, would they have paid anymore attention to it than the audible stall warning?