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.
Porn has never been considered 'free expression'.
Fundamentally, when the courts have been pushed to identify what actually is "protected speech", they are typically referring to viewpoint discrimination.
What this means is that anything that is actually espousing an opinion is protected speech that can't be restricted by the state. Incitement is a call to a criminal act, and isn't protected. Defamation requires a fact based claim, and is not protected. Porn is considered an "obscene" material that isn't actually espousing anything. It's a visual stimulant, and the court recognizes the need for children to be protected from obscenity.
Calling something "art" isn't enough. In fact, art is actually quite regulated, especially in the modern concepts of "performance art", where the performance can be so disruptive it can interfere with airspace, cause a general panic, or stop traffic.
For example, car shows are not protected speech, it's why some places can stop car shows from happening if they expect a disruption of traffic, or significant noise pollution.
What's protected is viewpoint discrimination. So we need to ask ourselves: "is there a particular viewpoint that this car show is espousing?" If the answer is yes, then we need to ask: "are the restrictions that the state is imposing being done as a response to the viewpoint of the car show, and not elements of the show itself." If the answer is Yes, then it's a violation of free expression / speech. If the answer is no, then the speech / expression is not protected.
ON THAT NOTE: are child drag shows a free expression? Absolutely not, specifically because of the violation of obscenity.
Thing is, most of the local governments are refusing to enforce obscenity laws on the drag shows because the establishment wants your children to be raped. However, the shows are absolutely illegal, and it's why a few of them have been shut down by the police after counter-protestors basically forced the police to show up by making a giant scene.
Porn, as far as SCOTUS is concerned, doesn't convey some kind of viewpoint. It is a product which is consumed for the purposes of masturbation. Basically, it's a 2D dildo. As such, this is not protected speech, but a commercial transaction involving obscene materials, and is therefore well within the government's right to strictly regulate.
What counts as porn is more subjective, quite literally "I know it when I see it". Probably because you actually know porn when you feel it, rather than see it.