As you took the time to explain all the acronyms I´ll explain a bit more about the context of the post.
Commercial pilots begin flying small planes like Cessna 172, then they fly a small multiengine with instruments, they also take lessons in small simulators. After this you must have a good (or very good) manual handling in visual and instrumental flight to obtain the commercial pilot license. Once you get more flight experience flying small cargo or aerotaxi, you get to flight medium turboprop commuters like a ATR-72, and then if you are lucky you get to fly in a mayor airline with 737 or airbus 320 before you can fly the big birds like 777, 747, 767, A340 or A380.
Once you are on a big plane, flying manually is almost optional as you can have the autopilot engaged from shortly after take off on climb, to 1000´ to the touchdown. Usually pilots enjoy flying manually, we do it whenever we have the opportunity, of course if there is a lot of traffic congestion and/or bad weather we keep the autopilot connected because the workload builds quickly (other traffics, avoiding thunderstorms, checking all the instruments for an auto-land, control instructions, etc..). In my case I was lucky to be able to start flying a B737 when I had only 200 total flight hours. My instructor was afraid that I will not be able to deliver due to my lack of experience, but I had no problem doing so (thankfully!)
It seems that in the Korean instruction method, obedience and memorization is more important than situation awareness and flying the plane. When this instructor tried to teach and measure the performance using the proper and internationally accepted method he was chased and punished by the airline establishment.
Just to give you some flavor of the difference between flying manually or with the autopilot I have this analogy, is not perfect but it transmits a bit the sensation between one and the other: Flying manually is somehow similar to how you ride a bicycle, you have to "feel" it, if you are going to be able to take a curve, or to brake on time, etc.. once you are comfortable with that, you don´t even have to think consciously any more about it. Going with autopilot, well is like going on rails, if the rail is not broken you know where is going and how, you only have to advance how to brake and accelerate (I Know that driving trains is more than that, I just mean a straight simple railway). Autopilots are a huge advantage in aviation, it allows to fly in much more congested airspace with much more safety, and with all the computerized systems, we are relieved from a lot of tedious monitoring.
It seems that the Korean pilots (this is the OP´s version, I don´t really know) have very limited experience and proficiency flying manually. He is surprised because most of the senior pilots were ex-military with experience in F4, F5, F16 fighters, etc.. I am not very surprised. I have flown with ex-military (Spanish) and the kind of plane they had flied previously wasn´t an indicator of dexterity. After all, combat flights can be very technical and planed (all points prearranged and studied). Thankfully I never had an experience nearly as bad as the ones he describes.
The flight data released by the NTSB shows a high approach (above the normal flight slope), first when you flight a ILS is very unusual to have a situation like that (constant 3º descend) because everything is controlled step by step 12 miles out of the airport. Second, if you are used (and like) to flight manually, disconnecting the A/P(Auto pilot) is what you are going to do (and enjoy), probably also the A/T (auto-throttle for boeing, the thrust levers move; or auto-thrust for airbus, levers doesn´t move), above all this, if you have normal skills flying you are perfectly capable of flying an approach from above or from below, is not a big deal, if you see you can´t do it you just turn around and try it again. But a pilot that is afraid and insecure of his capabilities, will try to do it with the A/P or with all the automatic systems available till the last moment.
Technically if you are above the normal slope, you have an excess of energy (altitude), to correct it you set the throttles manually back, that way you are able to descend faster (higher vertical speed) and capture the glide slope "visually" with the VASIS (white and red lights that let´s you know when you are high or low on the glide).
But it´s dangerous to land with the engines at idle, it is recommended that at 1000´ you must be on the glide slope and fully configured to land (gear down, full flap, speed at Vref[Vref is the reference speed for landing, is the minimum speed you will flight]). If not you must go around and try again.
DISCLAIMER, this is my opinion based on previous similar accident reports, the OP thoughts, and my own experience. The investigation may tell a very different situation.
It seems that the crew at the Asiana flight, kept trying to set the A/P or at least the flight guidance + A/T to descend and catch the visual path, this is very dangerous at low altitude, because you loose the situation awareness, AND you put all your attention inside. In that moment it becomes more important for you to see what´s happening at the panel (which is a big mistake), than to what´s happening to the aircraft trajectory (which is of course much more important). I can imagine a kind of fight against the flight guidance buttons to try to descend the plane. Once they got it on descend mode (I don´t know the 777 modes, but it´s not that important in this situation, in fact you must avoid them and flight manually), they realized that they had to slow the descend for the landing. But once you are outside the loop (flight awareness) it´s very difficult to get in again.
Once they started pulling back, the speed decreased, usually (this is surely what they expected), the autothrust would have engaged to keep the speed at the normal Vref (landing speed). But as they had touched the modes, the A/T didn´t engage and the speed started decreasing towards the stall. Then it becomes a matter of managing your energy, if you want to keep altitude you are going to end stalling, and if you want to keep speed you´ll descend too soon and too fast.
Surely they started noticing something was odd (too high nose, too low trajectory) but when they finally realized that they where going to crash and/or stall, and/or fall short (not necessarily knowing why), they set the throttles to full power and tried to go around, but big engines need a lot of time to go from idle to full power (usually you engage them slightly in advance to when you are going to need them), and it was too late to avoid the crash.
This may happen even to good manual flyers, if you are not comfortable flying like that it´s much more probable to have an accident.
Edit: added some explanation to acronyms, and improved a bit the text.