Ryan,
There is an art. I went around Arbor Links with Bill Kubly in May and he (as part owner) has actually spent a lot of time on site painting the eges of those bunkers to keep improving them from Palmers originals.
In short, he looks for bare areas between grass clumps, and leaves some clumps of native grass in the bunker, etc. In other words, he just helps the evolution along on the native side.
Some of those photos, with frilly edges against mowed turf don't look evolved. The simply look more curvy and just as some gca won't more than double the grades to maintain a natural look, I believe that in some cases, the amount of curves in a bunker shape might relate to the broader landscape. In other words, frilly edges probably tie in better on a sharply varying landscape, and simpler shapes seem to tie in better on gently rolling land.
Or, if we just accept that bunkers are abstract pieces of art, maybe the edges just need to be well done in terms of proportion, etc. Many of those jagged edges are really just smaller and smaller curves heaped on each other, not really random looking.
Short version, again, yes, its an art.