Mike:
I haven't ever called any golf course a masterpiece.
I'm not sure I would ever have used that term anyway, but the clincher was that Treetops in Michigan NAMED its first course the "Robert Trent Jones Masterpiece". 
It certainly does matter that the owners of a golf course care enough about it to find a good superintendent to manage and improve it. However, it only matters whether it's public or private to the degree that the owners with more money and more passion and more likely to make their courses private. That was true in the old days, but not so much anymore ... witness Mike Keiser, Herb Kohler, Mark Parsinen et al.
Tom,
I did think about whether or not to use the term "Masterpiece" but used it because it was used in the other thread which made me ask the question. But I do agree that it should probably be a word such as "exceptional".
And your second paragraph is definitely correct. The newer courses that have been created were what made me ask the question. Which brings to mind another question: I like the effort made at PD to blend the green perimeters into the surrounds seamlessly and wish it were done more but how does one determine when he can mark his ball in competition?
"Oh, the streets of Rome are filled with rubble
Ancient footprints are everywhere
You can almost think that you’re seein’ double
On a cold, dark night on the Spanish Stairs
Got to hurry on back to my hotel room
Where I’ve got me a date with Botticelli’s niece
She promised that she’d be right there with me
When I paint my masterpiece"