The most important change that's occuring on the planet right now is that we're growing out of the mass society, mass consumption, mass schooling, mass manufacturing, and mass media. We have finally begun to acquire the tools we need to really be individuals, to pursue the human adventure in its noblest form. The net with its inherently changing nature, and the array of promises it holds, including the end of mass media, the beginning of individual media, and the equality of it all, seems ideally designed to further this adventure. A democratic state should apply the wishes of the majority, but the rights of the individuals must be maintained, even when they go against the wishes of the majority. If the media is to be believed, most of that 'indecency' falls under sexuality.
Teenagers are probably the ones that are the most interested in sex.
They're naturally curious about it. Society has determined for them that they should be 'protected' from access to sexual information on the net. At a national and planetary level it's an impossible task, even if it were a desireable one. Technological advances go against sexual taboos. If 12 year olds want to know about sex they should be able to get information about sex , if they're not interested they won't look for it.