One of the major points discussed in the article you didn't read, WM, was the fact that bad press is invariably good for the sale of a game. Games that would otherwise fade into obscurity become a part of gaming history simply because of their violent or explicit content--and games that are already good, like Mortal Kombat, do even better in sales because the controversy gives them notoriety.
Another point they made, though not as strongly, is that fact that the people who object to game content are quite often the same people who buy it--unconcerned or unobservant parents. For every two people who complained about BloodRayne, I'd bet that one of them bought the obviously M-rated game for their child and THEN started complaining about it after they saw it in action. Self-imposed ratings are the smartest move the game industry has made in terms of content, because it allows them to point at the box and say, "look, doofus, it says right here that it's for Mature audiences only. If you don't want your child exposed to this type of stuff, then don't buy it for him."