Anti-censorship liberals will share this view. In struggling against censorship we also differentiate ourselves from such views. But opposing censorship is not the same as defending porn. Compared to censorship, in this view, the circulation of porn is a lesser evil, a price paid for free speech. This is at least equally true of most activities under capitalism, from office to sweatshop floor.
Capitalism does that with all our needs or passions.
Pornography is sexual. It is a representation which seeks to sexually excite us. It wants to turn somebody on. That, not sexism, is what makes it different. And it is that which should also make it a legitimate aspect of our culture.