I'll quote C.B. himself to try to address Geoffrey Childs' question (from "Scotland's Gift, pp.191-2):
"The seventeenth or Road hole at St. Andrews was, of course, easy to duplicate, but I determined that the station-master's garden should not be out of bounds as that is a forced situation, so I made it a great expanse of bunkers and mounds, so that one who played into it would find difficulty in getting out with one shot capable of making any distance. When it came to building the green, the size and bunkering were identical duplications with two exceptions. The sharp juttings of the bank running up to the green I made less unfair by smoothing the juttings off somewhat. I had read many criticisms of this flukey approach and agreed with them. Where the road with its mud, ditches, and walk are on the right of the green at St, Andrews, I built a formidable sand-bunker running the entire length of the green with a five to six foot face; therefore giving a player, unfortunate enough to get in, an honest golfing shot."