One thing that's got people's panties in a bunch is that he will neither confirm nor deny that that picture is him. Many people's hypotheses rest on whether or not the picture is actually him, and people in general are weirded out that he won't say -- as if he doesn't know.
Now, I'm not a guy. I don't know how much one knows about one's penis. I would think there would be things that are clues (for example, leaning to the left), in addition to the style of underwear being a clue. So why the hell won't he just tell us?
Well, why should he? If that picture is him and if he was pranked, then he has had a major privacy violation. No one should have pictures of their junk (covered by underwear or naked) circulated without permission.
Whether or not he was pranked, I doubt he intended to have the nation staring at a picture of his underwear-clad erect penis. I can't imagine how uncomfortable that would be. This guy knows that everyone who looks at him is imagining that photo and wondering what's under Weiner's pants. He could be denying information about ownership of the photo for self-preservation.
If he says yes, it's him, then everyone's seen him with his pants down. If he says no, then everyone's wondering is it bigger, is it smaller, does it lean to the right... There is no reason for gossip-column journalists to need to know this information. Police/investigators? Yes. Perez Hilton? No.
As for more legitimate journalists, it's their job to investigate. Subjects of investigation do not have to be compliant.
As for the American public, I don't know that it matters if the picture is him or not. If he sent the girl a photo of someone else's erection, that's
Note: wouldn't that be something -- if Weiner won't say it's his because he sent a photo of someone else! He was having some gay sex and tweeting to the girl about it... He took a picture of someone else off the internet because, as Jon Stewart put it, he's got more Anthony than Weiner... hmm...