Pat,
It depends on the circumstance.
At Barnbougle, the green site is a huge bowl with a lot of natural contour. I suppose we could have opted for a smaller green, but even then we would have had to flatten out part of it so the contours would be more in scale; and it is a long downwind par-3, so a bigger green made more sense. The big contours were already there, although I suspect many other architects would have seen it differently.
At Lost Dunes, the wild green at the fourth was more from my imagination -- a reaction to being at the business end of a short, flat par 5. On the other hand, the second-wildest green there, the eleventh, is a big natural bowl that I suppose could be compared to the 13th at Barnbougle, even though the contours are completely different.
My very first wild green, the fifth at Riverdale Dunes, was ordered up by Perry Dye who thought the course needed one. I was actually pretty pissed off that he didn't like the previous green I'd built, so I overreacted and gave him a really wild one. He never knew what he'd unleashed!