It's how parents raise their kids these days, or rather how they tend not to. It's so much easier to simply leave your kid with a sitter or by themselves for the day while you're at work or doing whatever, leaving the media in all its forms to raise the kid more than you are. Given what popular media tends to portray for the sake of money, it's not too surprising to see such immaturity.
Of course the other half of it is simply how the brain grows...it doesn't fully mature until you're about nineteen or twenty years old, though by fifteen and sixteen the only real aspect that still needs much maturity is the ability to fully think out long-term consequences of one's actions.
That's not to say it's not partially the kid's faults either...they really ought to learn how to be more mature and responsible too. In a way everyone is to blame.
I call bullshit. Parents on the whole never did a particularly good job of raising civil, erudite children, so it's not as though pop culture has ruined a previously great institution. Likewise, the dichotomy you are setting up is false. Parents are spending more time with their kids than in decades. (Which I know thanks to reading
the news.)
I have come to suspect that every generation believes the newest crop of kidlets is of lower quality than in ages past. I have also come to suspect that said belief is a bunch of hooey.