Mike,
Nice Topic. I had this discussion the other day with a client, who felt no greenside bunker should be so deep you can't see the pin. I've heard well known pros say the same thing - if you can't see the pin the shot is as much luck as skill.
I'm not so sure I agree but that idea is usually beat into me. Golfers use the old "what if I miss it here?" argument, claiming that making bogey from any particular spot is a problem on the order of magnitude proximate to terrorism and world hunger.
I have long thought that generally, bunkers ought to be proportionally deeper for short iron approaches. Isn't a green side miss with an 8 iron a bigger mistake than a miss with a 4 iron? If so, does that warrant more difficult punishment? On public courses, owners want speed of play and deep bunkers are thought to slow it down, so I rarely do this.
My other thought is that generally, if there is a bunker one side but the other is open you could have a deeper bunker than if you bunker all or both sides to give more room to play away from it if you choose.
I tend to bunker deeper on a long par 4 if the tee shot is relatively easy, and do fewer or shallower hazards if it is more difficult. Or, I make both shots hard and make the green flatter.
As to green slopes, I have heard good players say they always want the green to slope towards the bunker, with one even saying water should drain into the bunkers, in case he is playing to a tight pin near the bunker, and he doesn't want to have the ball roll away from the pin.
I think that is overdoing it to make it easier on those players, while making it harder for the superintendent.
I may make the collar higher and more steeply sloped toward the green surface on longer approaches to help hold a skittering approach shot on the green (esp in cross winds) but this has the effect of making the recovery shot harder when you short side it. So, which is more important? I think the former, but there is holy hell to pay when someone misses and makes bogey from that bunker.
As Pat alludes, with lob wedges, I'm not sure extra bunker depth is a bad thing in a "pure design" and a green sloping away from you is lnot impossible, but still harder than hitting into the slope. If a course has some of each, its just something the golfer needs to know and learns over time.
I will be interested in hearing other thoughts.