All of those lacy edges on the bunkers at Augusta were simply edged off over years, and no one's tried to put them back. Instead they've preserved/restored/emulated the shapes and sharp lips created by decades of edging. You also see a number of sand faces at Augusta where the original edge has been cut back so far that a weird, bulky shape in the bunker cavity has been created.
Of all the world's great courses, Augusta certainly has the worst looking bunkers. They really just look like bunkers that have lost their original character over the years; only difference is, they're filled with really expensive white sand! This phenomenon has occured at so many aged course, but it looks most bizarre at Augusta.