I'm afraid you're ignorant on this. The video game industry is very much marketing and developing toward adults. I play a lot of video games, and read a lot of media on video games, and it isn't geared toward children. The average gamer nowadays is between 20-30 years old. I personally know a crap load of people that fit this mold, many of which own a copy of San Andreas.
You are right. They are marketing towards the generation that grew up playing the original NES. Personally, I would never let my child play San Andreas, but that doesnt mean that I dont enjoy the heck out of it! (Similar to a good cigar.. oh wait, hope the anti-tobacco people dont show up on this thread too :P)