Very interesting thread. I think it is a mistake to attempt to qualify a difference, especially with some as finite a "a line".
As with many topics here on GCA, there is an attempt to gain an understanding of an element of design by examining just one parameter, to develop some sort of litmus test. I think this thread is a good example of how one must bring a myrid of other parameters to bear on such a discussion.
My take is that there are too many variables. Perhaps the biggest ones having nothing to do with the physical course but rather the psyche of the player. What his baseline is, what his expectations are. Perhaps that's why we aren't all married to the same women. We all have different tastes Taking the analogy a step further, look at the divorce rate. They all loved it (her) enough to think they wanted to spend the rest of time with them. However, either taste changed or they discovered enough annoying things (some which may have been initially endearing) to cause a change in heart.
Trying to qualify or quantify an abstract concept is a fool's errand (leading to the "I know it when I see it" conclusion). But, in the process, it helps identify elements of the concept which one person may have looked past. Distilling this thread (leaving out the Fan Club sidebar) it seems there are a few common denomenators like boldness of contours relative to green speed, alternate routes vs make or die, architects reputation in the hands of maintenance decisions/personnel, a simpathetic (to the surrounding terrain) aesthetic, green size vs amount of contouring vs anticipated approach shot in, ability of the turf to allow for pitch and run vs an "aerial only" approach, etc.
Of these parameters, the one that GCA's don't have much control over is architects reputation in the hands of maintenance decisions/personnel. Therefore, this, more than any other reason is why most GCA's tend to err on the side of less "wild,crazy,fun" because "stupid" is just around the corner. Ironically, (was it Joe Dye?) who said "we (the Tour) are not trying to embarrass the best players in the world, but rather identify them"? Heavily contoured greens can add another dimension to the equation. As for the "you can get there from here" arguement, when I posed that early in my career to a long time PGA Tournement Director, his response was "if you are there but want to be here, obviously you have played the wrong shot. Why should you get the same reward as one who hit the correct shot?" Unfortunately, and here's the rub, recreational players don't have that degree of accuracy in their game and hence have a different baseline of expectations. In his world he "expects" just being on the green enough of an accomplishment to be rewarded with a possible one putt.