The use of cellphones and cameras is so widespread and common now, that I think it all must come down to common sense.
I understand the band's position, especially from the "artistic" side of things: "Geez will you stop taking pictures and just enjoy the performance I'm giving you"?... the pictures themselves are good promotion however, nobody sells a (even good and professional) picture, what's the financial harm in having a good picture? it's free promotion!
What I mean by common sense is "Take some pics here and there, but don't stand with your arm raised the whole damn time" as many others have said. I'm an amateur photographer, and I love to take pictures at concerts; I have always my camera at hand, and I take a lot of pics, but I still enjoy the concert. I singalong, I jump, during songs that really move me I even forget about the camera and stand there in adoration, but I never stay with my camera held high all the time. If the band releases a video of the show after the tour makes no difference for me, I want a visual memory of *my* concert, of what happened when *I* was there.
It's irksome to see a sea of displays when looking at a crowd, but as long as someone does not annoy everybody around it, I don't see such harm in the "Take a pic, put the camera away, enjoy the song and take it out again 'cause the singer is in front of you or fireworks are going out" approach.