The ESRB is a fantastic idea. It's an argument that the industry can pull out and wave at politicians every time they call for tighter regulations on games.
"Hey, we tell people right on the fucking box that this game isn't suitable for children. Are you telling me that parents these days are too stupid to read a box? IS that what you're saying, Mr Politician? That Parents of children, the people who's votes you are seeking, are nothing more than clueless retards who couldn't be trusted with a can-opener, let alone raising kids? Is that it, Mr Politician? Because it certainly sounds like this bill restricting the sale of videogames to minors is you blatantly calling your constituents fucking brainless morons right to their stupid faces"
That's the argument in brief. Say it loudly and publicly enough and it's quite effective, too.
Without your ESRB, you'd have something like the Australian OFLC, where videogames are for children because one fuckwit in South Australia has the power of veto. So stop whinging about it and be thankful.