I have couple objections:
1. Nudity is not sex. Depending on how it is presented, nudity can be completely nonsexual.
2. The system seems unnecessarily strict. For example, games as seemingly harmless as Pac-man and Asteroids technically qualify for Intense Violence (STRONG) - Depcition(s) of realistic or non-realistic characters commiting acts of violence that result in death and possibly bloodshed. However, there is a world of difference between those games and, say, Mortal Kombat.
3. Nitpick: depictions of extreme horror should in some cases get a strong rating.