Steve,
Yes, what a green can't be sometimes becomes the focus of design. As I often say, though, its not only not nice to fool mother nature, its not possible either. Therefore, the number of pin locations needs to be tailored to the expected play of the course. I design mostly high play public courses, or ones that we hope are high play. You can be a bit less stringent at high end private clubs expecting only 12K rounds per year, obviously!
It takes 21 days on average for the cup and 3-4' radius where the feet of all 200-250 golfers on a weekend day tread to heal from the beating. In good growth weather, or on low play days (probably 50 players or less, although I don't know exactly what that number might be) recovery might be quicker. On private courses, I might plan for as low as 12 distinct cup locations (6 day of play times 2 weeks). On public courses, I usually plan for 24 distinct cup locations, just in case a few prove unpopular - 4 each on a 2 wide by 3 deep grid - which does start to limit the areas where you can do extra contours of any kind on an average size green.
Somewhere on my cybergolf series I did the math, but that comes out to about 600 sf and a minum size green comes out to be about 4000 sf. With more contours, there is in reality, much more unuseable area, such as not putting pins near the edge, on tiers or steeper slopes, etc. but much can be accomodated on a 6000 sf or larger green. I once described here how a six inch knob in the middle of an otherwise good cup setting are takes out gobs of useable cup space.
Pat,
See above. It is traffic pure and simple when it happens, or dispersing same. The USGA spec has no limitations that would prevent more contours. Owner/developer reluctance might - if they are concerned with speed of play, again mostly confined to public courses. And with greater speeds, there is a reluctance to put a pin too near a tier, knob, etc. since its harder to stop a putt at a pin guarded by those. I think good players complain about those kind of pin settings far more than average ones.
Lastly, the sad part is that most golfers don't really want the course to cost them strokes. If the Owner/GCA are reluctant, it may be that they are reluctant to accept inevitable criticisms.