Slag,
The idea is to make it look as natural as possible. You can have artifice as long as you emulate nature exisiting as close as possible. Especially on something that Mother Nature never intended to be a resort, let alone a golf course. The purpose is to to, in some cases, even recreate what may have been there, even before they found the property covered in whin.
My positives about Bandon Dunes is that the bunkering is well placed, in some cases perfectly placed for the strategies intended. (As an example, I'm always inclinded to think of Bandon Dunes 8th hole, more specifically the cross bunker. But not just thinking about the one paticular hole--all of them.) The negatives are the grass facing which is the result of being motivated on how they do it in Scotland in the modern age, which is being pushed by the American specification of clean and neat, yet baring the years of evolvement that has occured in the land which the game was invented. There is little doubt that many superintendents will find this bunkering totally acceptable because it is easy to maintain if you don't mind fly-mowing compared to having to push sand back up bunker faces that has fallen due to rain. On a site like that, you have the wind blowing at different angles during different times of the year. etc. etc. etc. It just shouldn't look so manicured. But its just not an esthetic issue. In fact, it isn't. It is how they were designed to be maintained, and the person maintaining them is doing his job.
I buy into the natural bunkering scheme of things. It is my personal preference, and I think that is why this site is so intriguing, we are allowed to expounce it!:) I'm not just talking rough and irregular edging, but more the ideal of lesser maintenence means ugly, knarly, threatening bunkering which I feel should affect the psychology or the mindset of play as well as llook totally natural, even though it may in fct be constructed. You know, the type of stuff I don't mind being in because it is fun to take on life's trite and biting challenges. To some, they will reckon, the bunkering at Bandon Dunes to be dark, deep, and just as threatening. That's OK. It just needs to emphasize this wonderful natural sandy bluff of dunes, and embrace the nature by emulating a bunker that looks as if it is a natural extension of the the very place you are standing, albeit a constructed one.