Neil, honestly I think a good bunkermeister can build and stylize anything and tailor it to the native soil, turf, and weather conditions.
I'd offer Bruce Hepner as an example. I observed him plan our some course reno, and particularly bunker reno at a course here in my area. I'd say they were something on the order of the work done by Rennaisance (Urbina's work I believe) at The Valley Club of Montecito. In my estimation, they are in Valley Club's, real MacKenzie reno, and in North Shore, a tribute to Mackenzie. They seem to have a methodology of construction that follows principles and techniques that allow them to properly cup and segment different areas within those bunkers, and properly drain them, and leave it to the supers to maintain them properly according to design intent.
Yet, these same archi-constructors have done completely different styling where a different approach due to the native conditions require. Same with the C&C crew and a great number of operators and designers. (there are a lot of talented people out there that don't have enough work) They all have internal company culture of construction techniques and methods, that I"m sure those bunkermeisters learned through trial and error, and what works best. I just happen to think that within rational imagination, everything about style, construction method and techniques, along with all known materials has been tried. Nothing new seems to be on the horizon of technology or materials development to alter the choices radically to a new direction in bunker design.
I don't think the construction and method has gone full circle per se, because these craftsmen are still doing various style, all within their personal repertoire, when and where called for. So, they keep changing it up rather than returning to settle on a given construction, technique, or style.
Would you agree with that?