In response to the term avant garde, i'd like to quote that master of the dramatic bon mot, Martha Graham; "No artist is ahead of their time they are of their time. Everyone else is merely behind the time."
However, on the subject of painting and sculpture promoting extreme uncture, well, there was the outrage at the impressionists first public exhibition, ditto at Manet's Olympia, not to mention, the slashing of the Rokeby Venus by a Suffragette and a hundred other such attacks on art. Nor must we forget the bad habit of British Colonial art plunderers who took it upon themselves to smash the genitals from the anciet masterpieces of the Greek and Egyptian sculpture (though would that be seen as shock at the retro garde?)
Also there was Hitlers degenerate expressionist art exhibition where he inadvertantly assembled the greatest collection of German expressionist art ever with the intention to shame the artists for their "perverted" artistic sensibilities, and of course the less sensational artisitic statements of the British young arts scene which the tabloid press love to get in a tizzy over.
The point I'm trying to make is, I suppose that art all art, if it contains the power to affect the viewer on a deeply personal level challenging moral mores, has regardless of the medium prompted strong emotional response. Though I suppose also Diaghilev and Nijinsky had the element of surprise on their side, no one knew what they were getting till it was served up to them. PR is nowadays sophisticated enough to know that the public will benefit from the advance warning that they're in for a good shock.