Steve,
Ya know, I even thought that as I was typing. Besides the 9 holes, I did run across a 12 hole course once and actually think that is the best solution to our time problem in golf. I know club pros would argue that handicaps, etc. would be confusing, but I don't think its an insumountable problem.
Pat,
As to vertical slopes, the other day after a Langford discussion here, I put a protractor to some of the photos Langford bunkers and grass bunkers in the Lawsonia profile. It appears to me that Langford bunkers steep banks vary from 1.5-2 to 1, with about 1.75 to 1 being average. They seem to do fine in Wisconsin, and I wonder if your vertical slopes in New Mexico struggle more than that because of your climate.
I also suspect that sand bunker slopes could easily be steeper at your course than, say, Nuzzo's Houston course because of the dry climate. For either, truly vertical is impossible, but steep may be workable in different climates.
Short version - your comment might be regional and not universal!