I am surprised that there has been no mention of the monitored approach concept. Obviously it is not AC SOP but do other North American operators apply it?
Marginal Wx or any non-precision approach - FO flies, Captain monitors and acquires requisite visual cues approaching minimums, while PF (FO) remains on instruments. At minima, FO/PF calls "decide" and either the Capt has the required visual cues in which case he says "continue" or "landing" and assumes flying control or he says "go around" and the FO executes the go-around.
The benefit is that when landing the Capt already has the visual cues and the PF does not now have to start assessing visual cues after minimums. Conversely if the visual reference is not there, the FO is already on instruments and in a better position to execute the go-around.
It seems from the report that the PM called "lights only" at minimums, which was then followed by further assessment by both pilots as to what they could or could not see - all below minimums. I'm sorry but the decision to continue or go-around must be made at minimums and based on solid visual reference. There should be no decision-making and discussion process happening under minimums.
I also note that no additive to MDA was mentioned. It is fairly standard to add say 50 feet to MDA on a constant descent final approach. The value of 50' is actually in the Boeing documentation for Boeing operators. This allows a go-around to be executed at minimums (MDA + 50') without breaching the MDA - which is a "hard floor".
Lastly, was there perhaps a culture during ILS approaches of continuing despite adequate reference knowing that the airplane will deliver the aircraft correctly to the runway and you will eventually see what you need to see?
Obviously with that mindset during a non-precision approach you will come short (no pun intended) due to the aircraft not "knowing" where it is relative to the glidepath.