The easy answer is 'both', of course. Like every tool we've invented, the Net can be used for good or ill. The extent to which it is ill-used is not its fault, any more than it's a car's fault when someone is run over. So many people--overwhelmingly older people, say, 45 and up--believe the Internet is a vast shadowy jungle, where monstrous things lurk, ready to tear out your soul and eat it raw. They are right...in part. The "World" part of "World Wide Web" is literally true: the 'Net is much like our Earth, civilized and urbane in many areas, wild and insane in many others. People young enough to hear the word "mouse" and not think of a rodent have a different view. They're intimately familiar with their own little hamlet on what used to be called the "Information Superhighway"....and familiarity only breeds contentment in their elders.
They're bored; they want to explore, and the dark places have an undeniable allure. So they poke and prod, and the more reckless of them are claimed, in one way or another, by the spiders that do lurk in the web.
When the Net was birthing, optimism ran high: here was a tool that could be used to connect people, to facilitate truly global perspectives...ultimately to save humanity from itself. Before this thought had been fully articulated, pornography and worse had taken root--and the soil of the Net is fertile indeed. We all know the majority of Net traffic is connected with smut.
Of course, it's an even bet anything "we all know" is wrong. Lo and behold, according to The Straight Dope, while sex is indeed popular, it ranks well behind music and (surprisingly, to me, at least) travel as a search item.
It's true that hardcore porn is trivially easy to discover online. Before my spam filters evolved into things that actually worked as advertised (I haven't received a single spam email in I can't recall how long), I often used to get such...