StephenB;
The expert on Max Behr is Geoff Shackleford, although I don't know that he'd call himself a resident here.
You asked;
"....what is/are the effect(s) that Max Behr's writings have had on Golf Course Architects, both past and present?"
Good question. Probably the biggest effect he had or has on architects both past and present is to make most of them scratch their heads hard and say things like:
"What is it this man's talking about exactly....?"
or,
"Wow, this guy might be deep, must be deep--I just wish I could understand him better to figure out how deep!"
or, in a letter by Hugh Wilson (architect of Merion) to Piper or Oakley (something along the lines of);
"Have you read Max Behr's remarks about Merion? I think the man may be completely brilliant but until today I didn't realize what I was doing at Merion East was helping to save the world." (apparently Behr had said something remarkably glowing about Merion East in his usual semi-inscrutable prose!).
But seriously, it's sort of hard to say what the effect of his writing was on architects past and present but I think GeoffShac has some idea on that from a few things he may have come across relatively recently. Apparently Behr may have had a far larger effect or influence on Mackenzie than most have known. Perhaps on Bob Jones too.
C.B. Macdonald was a friend and perhaps an admirer but C.B once made a reference to some who think way too much on certain things about architecture and I believe he was referring to Max.
On present day architects I doubt his writing has had much effect simply because it's never really been compiled. But thankfully I think Geoff Shackelford plans to do something about that. What's probably best of his writing on architecture, though, is these so-called "essays" that were basically written in the 1920s with that noticeable interconnecting theme which is probably his overall philosophy on golf and architecture.
I'd say the most recognizable thing he may have left with architecture in an actual concept sense is what's become known as Behr's "Line of Charm" concept. Basically that concept involved putting a bunker exactly in what Behr referred to as the golfer's "line of instinct"--that being almost exactly where he instinctively wanted to hit the ball, most likely on a direct line to the green or flag or obvious target.
With a bunker, for instance, in such a place Behr felt the golfer was more inclined to challenge it or at least have to deal with it by playing over it, on either side of it or short of it--basically up to four different opitons and it really can't get much better than that strategically.
Behr's underlying idea on this was to induce a golfer not just to think but also to feel he was really thinking for himself--finding and formulating his very own strategies instead of what some architect dictated to him with one choice for reward and the rest failure type of architecture--ie "shot dictation" architecture--or "down the middle only" type architecture.
With his highly strategic philosophy tailored to a golfer's very own choices, logically Behr believed in extremely wide fairways and he basically didn't much believe in rough. His concept was that strategic architecture was all that was needed to create risks and rewards. His feeling on hazards were they should be there more to inspire a feeling of temptation, challenge and potential exhileration in a golfer and less of a feeling of potential penalty and defeat.
Behr didn't like what we've come to call "architectural dictation". He felt an architect to do his job properly had to somehow create in a golfer a feeling of freedom of expression to do his own choosing which would allow him greater exhileration in success (reward) and also less criticism in failure.
Behr very well may have coined the term "Natural School of Architecture". If he didn't he certainly used it as a general description of all the things he thought golf architecture should be and do.
PS;
As I mentioned above Behr was apparently a far greater influence on Bob Jones's thinking on golf architecture than most have known and it has recently come to our attention that Jones's famous line was not "Golf is just a game"--it was, in fact----"Golf is not just a game, it's a sport!"