"Regular" is strongly influenced, if not completely defined, by what you see around you. Porn might partly reflect what people want but it also definitely changes what they want. e.g. http://news.ycombinator.com/item?id=1124922 People who watch porn are only learning how to make porn.
> "People who watch porn are only learning how to make porn."
That's a very narrow perspective. I can honestly say I have never felt like a porn actor (or director) in the bedroom because I watched porn as a teenager (to which I also attribute my ability to draw, FWIW...).
If there were magically a safe partner for everyone at all times, regardless or age or circumstance, I have no doubt there would be less porn. But we don't live in one of those worlds, we live in an emotionally-wrought, often isolating one. Teenagers feel alone, yet it's also a time when the instincts and cravings are the strongest, the most out of control, and the least satiable. The type of flirting and friendships I can take for granted, are not even on the table for them. Teenagers are still cutting their teeth on their communication skills. They don't know how to cope with a lot of things, one being the deeply-rooted drive to procreate. Pursuing those feelings safely can be difficult. Masturbation is one way for them to explore their feelings in the _safety_ of their own room - to take control of their feelings - without resorting to extremely poor decisions (unwanted pregnancies, unhealthy relationships, getting tattoos that claim they will love someone forever when all they really wanted was to see them naked...). Would a real partner be better? Perhaps. Is that always the best option? No, and I think it's harmful to act as though it were. Everyone has genitals and the feelings that go with them, but for better or worse, society pretends young people don't. For lack of a better term, they are screwed; they are on their own: they get to figure things out, hopefully without ruining their life in other ways.
Some forms of experimentation are more dangerous than others, and watching porn is one of the least dangerous options available to young people to explore their feelings. Ignoring that (prohibition, for example) won't help. Assuming we emphasize the difference between fantasy and reality, porn can serve a person well over the years. In that spirit, I would much rather see a "this film is fantasy, and does not necessarily reflect a healthy realtionship" warning on porn, rather than all those copyright threats... It's pretty obvious what our priorities are.