Ian
Fantastic post and makes me think that a principles-based approach is least likely to produce inherently-flawed tracks. The idea being that principles tend to focus on the bones like routing and bunker positioning so that even when aging transfigures the skin (eg bunker aesthetics) the play of the course isn't diminished -- the functionality remains.
I am not sure of my opinion below but thought I'd throw it out there to see what you or anyone reading thinks:
For me MacKenzie took things to a different level as he was the first really to apply psychology and the subjectivity of experience to design. For example his goal of of "greatest pleasure to the greatest number." As we all have modernist sensibilities we forget how we see the world differently than say the Victorians; we take for granted phrases like MacKenzie's but time and again in his writings he notes his desire for design elements to evoke certain emotions such as joy and fear. That's a subtle but significant break with the past. There's a lot of Frank Lloyd Wright in him.
In fact he writes of the value of psychology to the architect; I think when he writes of "psychology" he means more: to understand how the mind processes visual inputs and then to design according to that understanding, but fundamentally with a view towards the impact of the physical on the emotional and the mental. (Interestingly, many in critiquing a MacKenzie course will express that impact in terms of the physical appearance -- the skin, like the look of bunkers or the beauty of his greens -- even though the judgment fundamentally is emotional. (For example, "beauty" implies the thing you're looking at provokes an emotion of some sort, yes?)
Every architect today must think to a far greater degree in this way than those of a century ago -- that's down more to societal impacts not MacKenzie's, but still he deserves credit for being the first to think extensively in this manner. (Lots of designers at the time may have made references to emotional and mental impacts; however, their writings do not go into the same depth or detail, nor do these impacts rise to the thematic and repetitive level they did in MacKenzie's writings.)
I think this is the great intersection -- the underlying connection -- of his two post-medical careers: military entrenchments and what came to be called "camouflage" and golf-course design. (Yes, they both should count as "careers," his contributions to camouflage were far beyond dilettantism in depth and beyond dalliance in length.)
A close reading of his texts in both areas confirms he saw the two as not inseparable but of a piece: both derived from the same fundamental "principles." The only significant difference lay in the application of the principles. For example, the appropriation of "nature's principles" to either hide something (military entrenchments) or reveal it (bunkering). And of course in many cases the application converged to the same point: not to turn the manmade into the natural, as I think many tend to automatically think of it, which of course is impossible, but to design and build so as to give the manmade the appearance of the natural to the mind's eye.
Nature as a means to an end not as nature for its own sake. That end being to provoke an emotional response...
Mark