Something that was purely theirs is no longer theirs, now they have to share, and some can't stand that. Unfortunately it devolves into insulting the new initiates and the general masses.
There is something to this. But I think it has to do with devolving Star Trek for mass consumption. Not that new people are joining the club.
Yes, this devolution was my greatest fear going in. The early trailers and PR releases didn't help, and STID looked like it was aiming for GI Joe with a side order of Transformers. But to my surprise it is overwhelmingly about the characters, and treats them in such a way that my wary acceptance of them in ST09 has seemed to have blossomed into genuine affection.
I don't think it is JJ who has "turned" Trek. I honestly think it's the other way around.