I'm thinking the same when I see those fans with the phone up at concerts, like you pay so much money and have (often uniqute) opporunity, just to focus on your phone
There's almost always semi-professionally shot HD uploads of concerts from somebody else so nobody really needs to watch their own potato recordings if they want to relive the concert. A few short videos and photos is all well and good but I don't see the appeal in watching the whole concert through a screen when you can do that at home.
I think most idols really appreciate it when people put their phones down as well, they have cameras pointed at them all the time but it's a rare opportunity for them to connect directly with fans.
I've been surprised in my recent concerts just how much personal attention I got from idols on stage, I'm nobody special.. The only thing that separates me from almost everyone else is that I'm looking at them while everyone else is looking at their phone. Looking back at it that's my favorite memory of the whole experience; being noticed and feeling appreciated and smiled at by the people I support. I wouldn't have that memory if I spent the whole time trying to get the perfect picture that could never do the experience justice.