In the art world something is "edgy" if it might well shock ordinary folks, but of course not in-the-know folks. The idea seems to be that ordinary folks are shocked too easily by things that should not really be shocking.
The opposite concept, which I’ll call "anti-edgy", is of something that does not shock ordinary folks, but should. In the know folks are shocked, but most others are not. Why does the world of art and fashion emphasize the edgy so much more than the anti-edgy?
Alex Tabarrok has a paper on avant-garde vs popular art that can be found via his page if you have JSTOR access.
The problem in this prompt is that it divides shock value into two mutually exclusive groups: that which shocks the public and not artists, and that which shocks artists but not the public. The goal of most artists that aim for edginess is to shock everyone. The problem is that most fail to shock the desensitized artist population but can still cause a stir among the general population. There are some, however, that have succeeded in being truly edgy (eg Manet, Miro, Picasso).