Insofar as viewing rights to pornography are for sale on the internet, the very nature of the internet makes such sales "commerce with foreign nations, and among the several states" and for that matter with wired "Indian tribes." Unless there were some way for an internet porn site whose administration was located in, say, New Jersey, to guarantee that only New Jersey residents would have access, such a site is engaged in international and interstate commerce. Furthermore, free internet porn sites are typically supported by advertising, largely by pay sites, and so are adjuncts to commerce.
As Justice Story points out in his Commentaries, Article 8 makes no statement whatsoever about the motive for which the regulation of commerce is put in the power of the United States. "A power to regulate commerce is not necessarily a power to advance its interests. It may in given cases suspend its operations and restrict its advancement and scope."
The interpretation you suggest putting on the commerce clause make a mockery of the whole idea of limited government. Your intepretation leaves the federal government to regulate virtually every facet of our lives. This was not the understanding that the founders had of the authority of the federal government.
One of the rules of statutory construction is that you should interpret statutes in light of the problems the statute sought to address. There were two problems that the commerce clause sought to address.
First, some states were putting tarriffs on goods from other states. Second, some states refused to allow goods from another state entry into their borders. These two issues caused significant problems with trade. These problems were among the main reasons the Constitutional Convention was held.
Reading the commerce clause in light of the problems to be addressed, and in light of the founder's understanding that they were instituting a government of limited authority, you can readily see that the interpretation you suggest is inappropriate.