I think you guys are generally a bit too much on the purpose of bunkers, which is to make a course more interesting and fun, not to simply be penal. Sure, at a course like Oakmont, which is designed to be harsh and penal, it may be appropriate to have extremely penal bunkers, however created. At other places shouldn't the difficulty of a bunker depend on where it is and what it is there for? For example, I think recovery from the rough on the leftside of the first hole on Pinehurst 2 is supposed to be more difficult than being in the bunker on the right because the green slopes right to left. If you simply make the bunker more penal, you could defeat the design of the hole.
Similarly, some fairway bunkers are designed to be relatively painless to make golfers think. The 6th hole on the South Course at OFCC is basically a knoll hole, with very benign fairway bunkers. Thus, folks in them have to decide whether to go for the green and possibly make a 12 rather than simply pitching out. Make them more penal, and eveyone will simply pitch out, making for a less interesting hole.
The difficulty of recovery from bunkers is important, but I think focusing solely on the penal aspect leaves something out.