-First of all, it is what it seems, it´s an elementary piloting failure. Once you disconnect the Autopilot and/or auto-throttle you must be first of all flying the plane on it´s envelope then navigating and last combating an emergency (if there is one).
-Second, I´ve heard first hand how the basic piloting skills like a visual approach or manual flying are very scarce in several Asian countries, one of them is Korean. This is due to the initial and airline training philosophy, for example Chinese copilots are not allowed to take the controls for landing or take off EVER (they have eternal training periods that are useless as they have no skills at all to learn ) I´dont know if this is true for all companies but at least several big ones work like this. Opposite to this in European and American companies, flight officers do half of the take off and landings due for the day, the only difference between a captain and copilot is that the captain is the one who decides the big questions, but the copilot is required to have the same piloting skills. In this case they were two captains one of them an instructor.. No words.
-third, there is an American instructor who wrote at Pprune (a pilot forum) about how for Korean pilots (trained in Korea), the worst emergency they can suffer in a simulator is a visual approach. Even worst than losing both engines or total hydraulic failure. They are scared to death of visual flying. . He was fired from Asiana for failing to pass the annual exam to one of Asiana´s top pilots for failing a common visual approach. It seems that due to the problems with North K. it´s not possible to flight small airplanes and practice the basic skills. I can not find the article right now, I think it was erased shortly after being posted.
-Fourth, it´s common to do mistakes with the flight modes while on final approach, both with airbus and Boeing, there are several descend and ascend modes, speed modes, and auto-throttle modes. But basically is that if you are high you want to descend faster, if you are low, you want to reduce your descend or even climb (in case of obstacles ahead), and you want to keep your speed inside the restricted limits needed to flight with the flaps for landing (too fast and they bend, too slow and you crash). When a mistake happens is normal to disconnect the autopilot and/or auto-throttle and take over on manual. But of course you are aware of what´s happening, is like going with the cruise control on the car, disconnecting it and failing to brake at the next light.
-Fifth, there are differences between airbus and Boeing, an airbus would have done an automatic full throttle to recover the low speed. But this kind of automatic behavior has other costs, for example the Air France´s A330 that crashed in my opinion was due to an overconfidence in such automatic recover. The problem (and this is my opinion) is that the pilot flying thought that just pulling the stick the airplane would do the rest to recover whatever he thought was happening ( Once it was in to a deep stall, it was impossible for the computer to recognize what was happening).
I think that crashing in crystal clear weather on a big airport just because you don´t know how to flight manually is a problem that some companies and countries have with the flight instruction philosophy, no amount of technology is going to solve that. Now Airbus is trying to increase the manual training of the pilots just because this same reason. They just went too far automatizing the flight, but airplanes and computers fail, and when they do it while flying you just can not stop everything to solve the problem, you have to land the plane safely no matter what.