Whilst most the cameraphones are crappy quality, there are a lot of people going to gigs with high end compacts that are exceptional at gig photography and video. You only need to browse through the gig photos on flickr to see some amazing examples, and check out what cameras they are using. No, they're not SLRs generally.
And yes, a lot of people are interested in them. Some bands even turn a blind eye or sanction bootlegs for download, so long as they are not for sale. Some are quite interested in fan shot photos and videos. The studios however tend not to be.
As for piracy. In most gigs, the audio track is copyright in theory, but the visual act may not be (I've rarely seen copyright even mentioned on the tickets, only stuff about photography forbidden which isn't the same thing). Studios and promoters tend to get their knickers in a twist over it though claiming copyright infringement (as they are the ones who stand to lose money, not the band as they pay the bands crap all anyway. Though how a bootleg deprives them of gig money is beyond me as going to a gig is an entirely different experience to a bootleg).
Copyright infringement anyway when you take a photo of something is a dubious argument many photographers would disagree with. Copyright is attributed to the photographer, not the subject. The legal aspect is usually the permission to shoot there.
The real criminals at gigs are the touts anyway, and there's no law against them.