This is a most interesting subject Tom, or as you say, a paradox! It seems to be a paradox that has been near the surface on this website for a long time.
I'm going to suggest to you that it may not be as much of a paradox as most think. It may not even be a paradox at all.
I think the reason it might not be is basically two things:
1/ The way we tend to look at those PARTICULAR architects from our unique perspective and the perceptions we have built up about them, likely with various misperceptions.
2/ The way they actually looked at their own projects and even their art (if we want to call it that--or they did?) sometimes with some very unique perceptions of their own that we might not be fully aware of or appreciate properly (in an historical context).
The best way to understand this, I think, is to go back and follow much more carefully the chronological thread of the evolution of architecture and also most definitely where--in other words, a distinction between Europe and America probably needs to be made at almost all times!
I think the first thing we need to do is to examine some of our own perceptions about various architects which are probably mostly misperceptions on our part.
We have clearly, on this site, cloaked some of these men in a veil of "naturalism", sometimes we call it even "minimalism". We sometimes say their first order of business was to search out sites for natural features to meld into their designs.
I think it's clear that MacDonald's first order of business was to build a course at NGLA that was 18 really good holes for golf period! His mission was to build a very solid course with few or no weaknesses or weak holes--that was his stated mission as he had proclaimed before doing this that there were no really good courses in the US and the vast majority were shameful. The actual construction "look" was likely much less of a concern to him, if at all, than the quality of the holes for golf, in my opinion!
MacDonald being Scotch/Canadian and growing up in Chicago had returned to St. Andrews in 1872 to go there to college where he became very interested in golf and under the tutelage of Old Tom. That was very early, not much more than 20+ years after the first rudimentary efforts at golf architecture ever. I think it's important for us to truly understand the chronological significance of that.
Obviously he returned some years later to study the holes he considered great ones to replicate at his planned NGLA. But what did he find in Europe then? Probably a number of desirable holes that were far more truly natural evolutions than a product of man-made architecture!
And the man-made architectural features he may have found on these holes were probably little more than rudimentary construction efforts to make golf slightly more functional. We've all seen the "sleepered" bunkers and such and they are anything but an attempt to blend into nature or the lines and randomness of nature. But they may have been functionally good for golf and also for the strategies of golf that definitely had emanated out of nature itself in a random way on the original Scotish links layouts, such as TOC.
So what I'm saying is what MacDonald was concentrating on at NGLA with Raynor, the engineer he'd picked to help him (who had never been involved in golf architecture before) was building a course of very superior "strategic" value throughout all the golf holes! And clearly the holes they designed and built, many of them replicas and replicas of pieces of holes and concepts of holes from Europe were extremely dramatic and interesting for golf--far more so than anything seen before in America.
And also what I'm suggesting is the golf and the apparent strategies involved were far more important to them than the fact that the holes might look manufactured or engineered or not! The design and the strategies of the architecture was from the truly natural layouts of Europe although the constructed features may have been not much more natural looking than some of the functional construction found on natural links courses which was the beginnings of rudimentary man-made architecture.
And not even being a golfer, Raynor went on and basically mimicked the style and also many of the actual holes of that original design--NGLA! And that's all he did, he never even remotely departed from that original prototype!
How did Raynor get so many good contracts and sites? Obviously with MacDonald's help and connections, particularly since NGLA was recognized as the finest course in America when it opened, just as MacDonald had intended it to be.
I would also dare say that NGLA was not just the first really good course built in America, it was also probably twenty times the construction effort than anything that had come before it! That's important to consider too.
It's also important to consider what MacDonald's inspiration was rebelling against! The courses that preceded NGLA were one of two things--either extremely rudimentary and boring, certainly by our present perceptions or of the shockingly bad geometric and symmetrical designs in early America which were not remotely natural or strategic!!
So I think we have to appreciate the chronology of all this much more than we do. MacD and Raynor were early, or early enough where the idea of constructing designs, holes, and features that were truly attempts to meld and blend with nature were not particularly important to them, if they even considered it. Good golf holes that were strategic and played in unique, dramatic and interesting ways were though.
I would say that it wasn't for at least ten more years that the idea of really blending with nature started to concern and intrique some of the American architects. This may have been inspired somewhat by the early Europeans like Park & Colt who had already built ORIGINAL creations in the heathlands--of course taking the principle of strategy from TOC, although the concepts and feature construction may have been more their own than what MacDonald did.
I also think that MacKenzie may have been the one to foster it along with his ideas of camoflauge and truly trying to make features almost indistinguishable from nature.
He spawned a whole group of architects that really did become fascinated by naturalism and how to actually construct to blend as much as possible with nature and who wrote a great deal about it and very well too. Architects like Thomas, Flynn, Hunter, Behr and Tillinghast, Ross and the others that really hit their strides in the late teens and particularly the 1920s which was the real meat of what we know as the "Golden Age".
And of course Raynor continued on doing the exact same thing he had stated out with at NGLA with MacD that was so successful; same early engineered style, same concepts, even many of the same holes right on through until the mid 1920s when he died.
So I don't think there really is a Raynor paradox or at least there shouldn't be! They were just trying to build great golf holes and if they happened to be highly manufactured looking and engineered, so what, as long as they were playing well and people liked them?!