I’ll add a third, not monitoring the picture outside the window. How many thousands of hours does it take to learn what an approximate 3 degree descent over flat terrain looks like?
vessbot, we aren't much in disagreement. But about the above sentence, perhaps the only thing the crew(in both the cases) was doing was keeping the aircraft on the correct descent path without the necessary thrust, manual or auto immaterial. That's why the speed was dropping. And when Airbus crew at 400ft realised the wrong mode the only solution was to try another time. It was early days on Airbus but thought that the crew which had come from basic B737 200/300 should have had manual skills because in many places they were doing visual approaches. In Boeing case they didn't realise at all. Boeing also had been asked to do something about the throttle hold as it can be confusing.