Pat:
I don't think it has much at all to do with what's perceived as "natural" v. "man made", at least any more than anything in architecture is less accepted when it's taken to be artificial. For the record, I've built maybe 3 or 4 greens out of 30 golf courses that were really and truly natural ... the other 500+ of them required SOME manipulation [often not too much] to get the slopes within reason and/or to make them more interesting.
Of course, the thin line you describe is a moving target, if the green speeds are going to change from owner to owner or from situation to situation. As Adam suggests, I think it would be next to impossible to create "wild and fun" greens for an owner who wants his greens to roll 12 or 13 on a regular basis.
[At Sebonack, Mr. Pascucci swore they wouldn't be that fast everyday, but that's where he tells his superintendent to get them during the season.]
My feeling is that is where Mr. Nicklaus is having trouble now. He wants to get wild and fun greens, because he understands it's the only way to make the course difficult for the pros anymore, and because he is more into fun golf than he used to be. But he is working for owners who want 13 on the Stimp, whereas most of my owners are fine with the idea of 9.5 to 10.5 on a regular basis and 12 to 13 only for a two-day event.
The other half of the equation is that when you are building in such short game challenges, you have to have a good enough short game to imagine every shot that might occur and to address the potential problems while you are building them. If you were going to hand that assignment to someone, would you hand it to Ben Crenshaw or to Jack Nicklaus? Building severe greens requires a much greater time commitment by the architect, because you are opening yourself up to criticism in a 3-D medium that can only be judged on site.
I used to have a pretty good short game myself, and I can still decide as well as anyone whether my greens are "crazy and stupid" or not. I know some people will call them that, regardless of what I think; but in most cases, it's because they have a poor short game, or a poor imagination as to how to position their approaches and/or play their recovery shots to give themselves a bit more buffer for error.
And Matt, I don't think it's all about whose fan club you're in. I don't agree with that at all. Perhaps Bill and Ben and I get more of the benefit of the doubt than others, because we've done it before ... but in the end, if you're not pointing to some of our greens and showing us where they are too severe, then it's not bias. If others' courses can withstand similar scrutiny, then they'll be good to go, too.