Do you believe this sort of pornography should be restricted, banned, or prosecuted or not. Please answer that question. If you do, then we are talking about where to draw a line. If you don't, then you don't have a line or have one way further out than most Americans. As for how mainstream it is, try Kazaa or the Usenet. Anyone with an ISP that provides uncensored newsgroups and a newsreader can get to it. Sounds pretty mainstream to me.
Perhaps you figure that some of us are not smart enough to see through this.
I want to see if you really believe that all pornography should be unrestricted on free speech grounds or whether you think some pornography should be banned or not. What I expect is for you to be honest enough to tell me how you really feel rather than avoiding the point because it makes you uncomfortable. If people really want to frame the pornography debate in terms of anything that's consentual is good, then let's talk about where that leads.