Seriously, what's the argument for porn being speech and expression? What is the message it's trying to convey?
Edit: Guys, I'm asking if it's speech/expression and, if so, how. Most of the comments in support of it aren't answering the question, just showing their support for free speech and expression, in general. Only one guy has made a case for it, comparing it to car shows and art. And, even though I have reservations about labeling it as art, I appreciate that he's making a case for it and not just side-stepping the issue.
First: Define your terms.
Second: PETA at one point covered naked women in pigs blood, and had them pose in oversized meat containers. There's definitely some kind of speech/expression there, you can argue the efficacy or sanity of that expression, but it is definitely present. But it is also easily considered pornographic, since it does feature, you know, fully naked women posing for the intent of gaining the male gaze.
"What is the message it is trying to convey" is a terrible question. Because Porn is not a message, it is a medium. "What is the message television is trying to convey?" is a useless conversation, because it lacks granularity. Is it left wing? Is it right wing? Is is neutral? Does it bounce between both? It all depends on what program on it you're watching.
Pornography is, at its core, a form of art. What does "art" convey? Well, depends on the art! Some art exists for people to discuss its deeper meanings. Some art exists solely to showcase some kind of technical skill of the creator, to other creators. Some art exists just to break up the monotony of a blank wall in a dentist's office.
I have a large painting of an armored apatosaurus being ridden by cavemen, fighting T-rexes. It's art. What does it say? Nothing. It's purely self-indulgent art. It is "cool". Looks nice too, good color balance and framing, but not enough to be a showcase in use of those things. A lot of porn is like that dinosaur art. It is self-indulgent art to look "sexy", while having a decent baseline of cinematography (no one wants 144p videos anymore).
Other porn can carry messages, like the PETA one above, or even showcasing techniques/positions/etc.
And yet others can shape society on a meta-level, while not being a message-carrier on the individual level. If all the porn "presented" to you is interracial, in example, you will likely vastly overestimate the demographical impacts of some races, even if any given video in the genre does little. In that case, the porn isn't the speech per se, but instead the presentation of the porn offerings is the speech.
And all of that is irrelevant... Because you asked the wrong question. The right question is "is it worth giving my political opponents the right to censor anything they wish by justifying it as them deeming it as wrong or lacking sufficient expression, because I don't like the idea of seeing other people naked?"