Carver, your low edge angle scenario presents a danger, but I'm not sure you're fully understanding the context of that risk. At low edge angles sudden twisting of the ski caused by terrain irregularities can be more easily resisted through maintaining rotational tension in the legs. The minor edge engagement with the snow at those low edge angles is more easily overcome, and ski direction maintenance more easily achieved.
The greater risk actually comes when terrain irregularities suddenly wrench your low edge angle ski onto a higher edge angle, and your skis "hook up" and crank an abrupt direction change right or left. Because of the low edge angle you were riding, your body is too much over your skis to be able to be propelled by the skis such that it turns with them. The result: the skis and the body part ways, body pummeling over the top of the skis, much in the manner Tog did with his.
This does not describe every manner in which to do an ACL,,, but from my unscientific observations over many years on the slopes its a popular one. I remember attending a presentation way back when. The Vermont gang had just compiled their data and recommendations on ACL injury and avoidance, and it was being handed down to our ski school. I remember thinking at the time that while their work was at the time ground breaking and valuable, some of their recommendations, especially in the area of "just fall and relax" sounded a bit difficult to follow in a sport where the general objective is to constantly manage balance and recover from occasional (or for some, frequent) cases of poor management. Deciding on the fly to suddenly abandon ship, and knowing the precise instance and situation when that should be done seemed to me to be a lot to ask. To be really safe using that methodology I would think one would need to error on the side of safety, and that would have skiers flopping all over the slope.
It's a tough situation to totally avoid,,, an inherent risk in our sport. We could go back to dead straight skis and low cut leather boots, and trade knee injuries for boot top fractures, but I don't think anyone wants to do that. I guess my best advice would be to work diligently on developing your balancing and edging skills. Acquire a keen sense of where your balance point is at any and all moments. Learn how to adjust it at will, on the fly, in any manner you choose. Also, learn how to perform at a high level in those less than ideal balance states. This will go a long ways in improving your ability to avoid getting into situations that carry the highest degree of risk. Learn how to manipulate your edge angle and usage over a broad spectrum. Develop your angulation skills, and stray away from knee anglulation as a default turning means. A long and strong leg, such that hip angulation provides, is your best bet. Go for outside ski dominance, as overly weighing the more highly flexed inside leg puts you on a weaker platform, and further aft, leaving you more prone to injury. Stay aware, look ahead. Ready yourself for undulating terrain by getting in safe states of balance and structural alignment. Relax as you go over/through rough spots so that your body can absorb and adapt to sudden changes without a stiff body driving the skis into an edge lock that allows the skis to take over as leader of the band.
It's a fun sport, but it carries risks. While skill development can't totally eliminate that risk, it can go a long way in avoiding it. 46 years on skis here, and knock on wood, not a knee injury yet.