From my observations after 10 years flying with Korean Air and China Airlines the pilots fear visual approaches and in general cannot fly them. Going into SFO requires special training and not all pilots are scheduled for this trip.
I did not fly the 777 but took the 744 into SFO many times. This approach is tricky and requires care, with attention to the glide path. There are restrictions that force the pilot to start a quick descent at each gate so as not to get high or fast.
Many of the pilots I flew with (and I never flew for Asiana) will not disconnect the auto pilot until around 500-300 feet when everything is set and stabilized. The auto pilot cannot make the necessary changes in glide path on such a demanding approach well enough to remain stabilized but the pilots persist because they do not trust their own skills to do it manually. Manual flying to them is using FLCH.
They are terrified of the FOQA system and know that any deviation WILL be caught and they WILL be called in to explain. Staying out of any FOQA report regime is very important to them, and for example if a descent rate of 1200 fpm is needed to arrive over the runway threshold at 50 feet, they will still try to remain at 1000 fpm to avoid the FOQA, reducing speed to make it down in time. Simply flying the airplane never enters their minds.
They get no training on visual approaches. Especially on line flights. I am amazed that they allow flights into SFO without any glide path guidance.
The FOs hardly ever get a landing and have no skills in this area. They are next to useless in seeing and alerting the pilot of any impending screw up. Especially with the rigid seniority, even if they did see something going wrong they would not offer advice, nor would the pilot take it.
If you search these forums for references to Korean (etc) pilots being unable to actually fly their airplanes, and especially unable to fly visual approaches, you will find plenty. I (and others) have been warning you about this for many years. There are many more pilots out there like this poor guy, who was given no tools or training to handle a difficult task and probably exceeded his skill levels. I do not know this pilot and never flew with him and he could be a much better pilot than I could ever hope to be, so this is surmise only.
When I worked for those carriers I got free or reduced fare tickets for my family but I never used them. I am personally amazed that we don't see these carriers destroying perfectly serviceable airplanes more often. The holes in the Korean Swiss Cheese are always lined up.