Most art of this genre tends to "preach" the traditional inhumanity of mankind of one sort or other. It's kind of a competition to come up with a new and improved (or innovative) inhumanity of mankind.
Mr. Tunick seems not to be preaching; just a deadpan, in your face, insistent, wall to wall naked bodies. Try as we will to peel away the facade of nakedness, to peek behind the nudity, to detect a whiff of meaning, to "get" the message. Nothing; there's nothing behind, below, or above. Just a seeming endless sea of bodies.
One is almost free to infer, or inject any meaning. Ahh, I get it; no I don't.

Just wondering why the article didn't reference Chinese artist Zhang Huan, who did some similar work in 94-95 or so, I think (To Raise the Level of Water 1 Meter, To Raise the Height of a Mountain 1 Meter) which I thought was more interesting. Not affiliated with him in any way, but saw the work in a touring show and was struck by it. Seemed to preach the humanity vs. the inhumanity.

Zhang Huan; http://www.zhanghuan.com/

Excellent work.