"Unless you wish to somehow eliminate porn globally"
Don't make the perfect the enemy of the good. Even if it can't be eliminated globally, we should make explicit our condemnation of it.
"or eliminate the Bill of Rights"
We really need to get one thing straight: the Bill of Rights was not written to protect pornography nor, properly applied, does it do so. It protects freedom of political speech and freedom of religion.
"I don't see how you can very well stop people from viewing porn produced outside the country."
That should not stop us from condemning the practice.
We can't stop people from committing murder, either, but we don't for that reason legalize it.
Whether or not the First and Fourteenth Amendments protect pornographic images, there would be no practical way to enforce a ban on the domestic consumpiton of imported porn without undermining the Fourth.
Further, I fail to see how it is somehow worse for someone to watch a video of a few couples having sex than for the person to pick up a stranger in a bar for a one-night stand. To be sure, neither behavior is conducive to finding a good stable relationship, but I don't think "normal" porn (as opposed to rape porn, child porn, etc.) is the problem.
Perhaps the ability for people to receive sexual experience or sexual stimulation by other means has reduced people's efforts to seek stable relationships, but there are many, many other factors as well. Women's lib has made it much harder to find a good wife, and much riskier to get married. IMHO, the popularity of alternative sexual outlets is a result of that, rather than the cause.