My definition of porn comes from Aquinas/Joyce- Art is defined by its aesthetic arrest- the viewer brings the emotional response to the work, the artist does not intend to achieve some pre-ordained effect. When the maker decides what effect to achieve and then crafts the work to achieve that effect, the maker is serving pornography.
Using Aquinas' definition, the primary function of DART is almost exclusively pornographic, we deliberately work to move viewers to specific results- emotional responses, votes, provocations, etc. These questions of jugs and gore are just our way of testing our own sense of propriety by defining someone else's- like some asshole driving the speed limit in the fast lane. I'm fine with just about any level of explicit sex or violence short of self-harm or the defamation of other users. Users should respect the norms of behavior within the confines of any debate or forum and as with all participation should avoid over-submission of unpopular content. If somebody want to change their profile pic to an erect penis, I'm fine with that. If somebody wants to post a link to an erect penis to a forum on third wave feminism, I'd consider that an abuse of norms. If somebody posts a bunch of dick pics all over the place, that is an abuse worthy of intervention by mods.