Pat's question is very interesting.
My perspective is that golf design is one of the least "fad-prone" of all the arts. Consider fashion design, industrial design, interiors, fabrics, theater, etc — there is little, if any, tradition that cannot easily be replaced in just a few months in these design endeavors. While in golf we always seem interested in the originals, even if the designs eventually depart...BUT...it takes a long time for anything to happen in golf.
Tom D. says: "Don't forget that "restoration" may be a fad, too..." I think this is a tremendous observation. Like the retro design of a re-done restaurant trying to appear as an authentic diner, some 'restoration' work is faux at best. But, that does not make it bad.
I still maintain that golf architecture is a very stale art form. If I were to land on one criticism for what we do, it is simply that new ideas and looks are a long while in coming, and they happen rarely. There are very few new greens, holes or concepts when you consider the volume of designs.