Answer:
Where maintenance is not an issue for smaller green sites, short 3s, 4s, and 5s.
"If they were dead flat and pretty big, then the low-handicap would often make par even after missing the green, and the player who hit the green and two-putted would not be properly rewarded." Tom Doak
It seems to me that by making the approach all that more difficult, thereby greatly increasing the probability of taking three additional strokes (putts or a chip and two putts) to hole out, that you are neither rewarding the player who hit two good shots nor penalizing the one who needs a third for the approach.
Take #8 at Rawls into the prevailing wind, with the pin 3/4 back and left. I'll be the proxy for a low-handicap player (I once was) and an infrequent player on the course. Let's say I can run up a well-hit three iron to the right front of the green after hitting a great drive, or lay-up short 50 or so yards after a so-so effort. My probability of getting it up and down from the front of the green is maybe 30 - 40% as opposed to maybe 10 - 20% from 50Y out. Soften the ridge and flatten out the bottom portion of the green and my probability of holing out in two putts goes up to 80-90%, while that from 50Y doesn't change appreciably.
I do agree with Sean. I enjoy a couple of unconventional, counter-intuitive, difficult holes in a course. I like a par 4 where I really have to bust a couple of great shots to reach the putting surface, and a long par 3 that has a challenging green but not overly guarded by penalty generating hazards. Unreachable par 5s are now the norm for me, but I prefer those which challenge not only the drive, but also the lay-up shot.