JES: Thanks for your post, which has really made me stop and think.
I would suggest that the primary reason for most courses having so many bunkers is that the architect believes he needs to do more "designing" to justify his fee ... or to make the player do what the designer wants him to do. (I suggest the latter because it's sometimes what I thought while working with Mr. Nicklaus at Sebonack -- he says he is creating more options, but in the process he is dictating what the A, B, and C player ought to try to do.)
I will agree with your assessment of the value of each bunker for a good player, because you certainly know the course better than I do. But, when you take out those 55 bunkers, will you have left the average player with enough interesting features to keep his attention and make the course fun?
If you combine the two viewpoints, then many modern architects have it exactly wrong -- they are putting in more fairway bunkers further downrange, when most of the fairway bunkers of interest to anyone are those in play for shorter hitters.
P.S. I do think a lot of the bunkers at HV are meant to get the members to aim to the high side of the hole, to help keep them from winding up in the fairway below.