It's not an issue anyway.
First of all, what would an app possibly deliver that you already can't get on sites?
Second, if you really need an app to download and organize, play, and share smut on, there are airsharing & downloader.
Who wants porn apps on their home screen anyway? "Oh sure, let me put your number in my contacts... oh uh, nevermind that, that there's triple anal fisting 4 app..." A whole app devoted to one... what, pornstar? Genre? Pay feed? I just don't understand what we're missing by not allowing "porn apps" in the AppStore.
And no, there is not just one app store. There is cydia as well, with numerous third party sources and apps. And yet, no real porn app proliferation there either. Why? Because there's no need. 9/10ths of everything on the net is porn as it is. ******* is already switching to html5, Youporn, redtube, & all the rest are working on it as well.
Most importantly, taking the official position of "no porn apps" in the app store instantly clears Apple of spending a penny on the myriad complicated legal restrictions regarding porn content and delivery that vary greatly from state to state.