The 4th at Pacific Dunes is a great hole and the ocean plays a part in that. The tee placement, the left fairway bunker, the bunkers left of the green, the dune left of the green covered with unplayable vegetation, and the depth of the green also play a part in its greatness. Both the site of the hole and its design play equal parts in its greatness. I was little bit disappointed to read Tom saying "The real genius was in making the desert out of bounds". If all of the design elements of PD #4 were in the middle of the Arizona desert, it would be a good hole. But, you would need to manufacture the effect that the ocean has on that hole. Dig out a large pond or lake? Slap some OB stakes all the way down the right? Both options sound bad. PD #4 is great because of the site and the design.Variety in setting and design make great golf.
You can't put 18 holes on the ocean and get the affect that you want. #7 at Old Mac and #4 at Bandon Dunes use the ocean to create something you can't get if you started on the ocean and stayed there. On both courses you know the ocean is there. When you come around the corner at BD #4 or climb to top of the ridge at OM #7, you are amazed at the scene and know that you will not experience it anywhere else. Yes, these holes are next to the ocean, but they are also well designed.
If you need an example of a bad course next to the ocean, try Sandpiper in Santa Barbara, CA. I can't imagine a course getting less out of its location that this one.