TMac,
I do remember your reply 11.
I have just returned from my morning walk in a park next door. Opened just a few years ago, it had several detail planting areas which always struck me as odd because I came out of LA school in the 70's, when it was clear that costs kept such detailed items from being included. Parks were trees and lawns, because that is easiest and cheapest to maintain. Somehow, a generation of LA's and Park Directors, who came up in the good times, have let themselves forget that maintenance cost is an important part of design. I noticed that they were removing said landscape areas in droves for cost reasons.
In my career, I have never forgotten the maintenance aspect of design. I figure if its too hard to maintain, it will eventually go away, whatever other design merits it had. There is no such thing as "pure design" in the real world. Cost is a factor for all but a select few courses.
My point it, I still don't think Tilly turned away from any design principle of his. He may have modified it to fit the times. Or, he may have ALWAYS had the "first" principle of giving the client what they wanted, and it was simply the needs of the clients that had changed.