I'm sorry, but I don't think small children should be taken to shows. If you want to take your 9 year old, and give them earplugs to protect their hearing, then fine. But, little kids have no business running around festivals like crazy. (I realize some festivals cater to those with kids and that's fine, but I"m talking about Coachella or things like that).
There just are some places where kids shouldn't be allowed. And people should know better than to take them there.