Cheeze, I disagree that its not about protection, or about empowerment. But, to clarify: by protection, I mean protection from being introduced to mature/adult concepts in an uncontrolled environment. In my personal opinion, it can be influencing for a child's first introduction to sexuality to be in hardcore pornography. The same goes for a child's first introduction to murder being with virtual knife in hand. By 18 (at a minimum, and hopefully earlier), a well-balanced offspring will have been introduced to all of these concepts (sex, death, alcohol, smoking, drugs), by an adult. This is where the empowerment aspect comes in. By having informative ratings systems that list which adult/mature themes might be contained, a parent can make sure that they introduce the topics in a controlled way, before leaving the child to explore the issue by themselves (through literature, videogames, movies, tv, or experience).
Some parents take these things, and try to use them to entirely shelter their children from what could be adult themes, forgetting that eventually, that child will be an adult facing the issue in real life. (These are failed parents.) Some people use the ratings as a weapon of morality. (These would be the people that Wal-Mart is afraid will boycott them if they sell AO games, or CDs with their "explicit" lyrics intact.) These people and their motives are not the ESRB's fault, and if we were to get rid of ratings because people abuse them, we'd be throwing out the baby with the bath water, so to speak.
Some parents, as you say, are more concerned with public opinion of how they raise their kids, than they are by how they're actually raising their kids, but I honestly hope this is a minority. Call me optimistic.
And to speak to your last comment, I (and possibly others) never meant either the former or the latter of what you surmised. To start with, I don't think it's "wrong to let kids play these games" at all. How about, "It's wrong to let kids play these games with no regulation or parental involvement because we--the adults--don't want kids playing these games until we've had a chance to cover the topics contained within in a controlled environment. Whether that be a birds&bees talk with your old man, or a sanitary, useless sex ed. class at school, I leave up to the individual parents.
This all comes back around to the real crux of the issue though: no matter how informative and helpful the MPAA or ESRB may try to be, nobody can really save all the kids in the world from bad parents. At least they're trying to help.
Edit: I was speaking to your last comment, before you made the un-identified edits. Your post changed between me responding, and me posting. So, by "last comment", I obviously now mean 3rd para.