You covered a lot pertinent ground, but you have not mentioned that a rigid pivot strut rod, induces a small arc in the LCA as it moves up and down. The OEM allows for this by using rubber I suspect. Almost all other LCA bushings, I suspect even the delrin bushing will allow that small motion. If that arc was resisted, you would have bind. Granted the induced arc is minor, but then those who are making this upgrade "think" they are reducing unwanted movement in the first place. I suspect the LCA might even flex in this new arc induced by a rigid strut rod mounting, since the LCA main strength is vertical by its greater height cross section. Of course those that add the lower rein forcing plate would reduce this flex, and therefore drift closer to bind, not a wanted outcome. All this means to me going full circle, not sure why bother with the upgrade if the installed rubber bushings are in good shape and tight, for anything short of Nascar
use.
For discussion sake, is there consensus the strut's biggest and most important loading is when under braking?
The purpose is to control the arc's of the strut and LCAs. As such, there will be a defined point during the travel of the LCA. With this defined point you can adjust/modify other items for beneficial alignment settings. If the strut is "floating" in a bushing, then the position of LCA becomes more dependant on acceleration, braking, or during turning as they apply force on the suspension.
