I gotta be honest, I have no idea. Though in my pornography kind of goes hand in hand with masturbation (or should I say cock in hand... heh heh). Though you don't really need pornography for masturbation but it does help speed up the process... not to mention various other positives for use while you j/o.
As for what future relationship problems this will cause? I have no idea.. I'm sure it's like anything you can completely avoid those problems if you don't try to hide it and raise expectations so that way your expected to act at a level that you really don't operate at. If its out in the open the people who like you will accept you for who you are and they'll be cool with that.
So really is it entertainment? No, I don't think so, I think its more of a tool to help assist in sexual stimulation. I can't see it being anything more. And if your opinions differ, then that's fine I suppose. I'm not going to judge you either way.. but I also expect that none of you will judge me simply because may use porn from time to time.. it's just whatever. Besides I think there are far better things to do then sitting at home watching porn all day.
So I guess mark me down for the undecided group.