PJ2:
Given the many comments however, I am trying to understand why the display has never been installed in civilian airliners.
As a U.S. Navy pilot, maybe I can give some insight to this. At least one reason is that there is prejudice against the use of AoA indications in transport and patrol aircraft in the Navy. The attitude has traditionally been that "jets are for kids". (This was primarily in the days when transport and patrol aircraft were all prop driven.) Maybe that attitude still prevails.
Navy flight procedures are codified in the Naval Air Training and Operating Procedures Standardization (NATOPS) program. Periodic review conferences are convened among fleet operators, the Naval Air Systems Command, the Naval Air Test Center, representatives of the Chief of Naval Operations, and the manufacturer of the aircraft.
In the mid 1960s, I was sent as the representative of the Naval Air Test Center to a P-3 NATOPS conference to review and approve proposed changes in procedures. The P-3 Orion was an outgrowth of the Lockheed Electra and had, as standard equipment, a direct reading AoA gauge. (Maybe someone can tell us if the Electra had an AoA gauge.) In accordance with instructions from my boss, I proposed and argued for the routine use of AoA in various flight regimes, particularly in landing approaches and in wave-off situations (Go Around to you airline folks). It would also be useful in an inadvertent stall situation (which you shouldn't get into to begin with). The conference would not have anything to do with it. Their response was literally "that's only for jets." They simply would not agree to use something that in fact provided useful information. Maybe that attitude still prevails.
In any event, whether a direct reading AoA gauge would have saved AF442 remains to be seen, but when you get right down to it, they broke one basic rule, "Never, ever fly through a thunderstorm!"