Libertarian? I'm not. So I'll just cut the philosphical argument short and say that we'll have to agree to disagree.
The only thing I'll question is your claim that the "US population" wants pornography. The soft and artistic Playboy type and the soft porn that you'll find on HBO or Showtime? Maybe. The hardcore stuff that we've both mentioned earlier in the thread? I doubt it. Indeed, that's how the government manages to get soccer moms and fathers to send pornographers to jail for obscenity. The people who like that sort of pornography are a subculture that makes up a fairly small fraction of the "US population". I suspect that a clear magjority Americans do not want to see women beaten to a pulp, people defecating on each other, or people having sex with animals. People only broadly support "pornography" because most nice people think of Playboy and not hardcover S&M when they hear "pornography". And all I'm really saying is that you should show people what you claim they support and see if their support is really as strong as you think it is.
And I guess this means you didn't read the section of the web site that I referened on prosecuting pornography, which defines the distinction between legal and illegal pornography, did you?