The whole point of parenting is to guide your children, either by directly monitoring them or indirectly guiding them with your values. If your back's against the wall, then sell the TV, turn off the computer, and let them play with Legos instead. There's an OFF switch built into those gadgets for a reason. Or use an intermediary answer, such as padlocks for the TV and Surfwatch for the computer. Okay, now let's look at the flip side of the issue, and see why it'd be good to have more pornography lying around the net.
Human beings are, by nature, curious creatures.
Give us an enigma, and we won't be happy until we resolve it, one way or another. Restrict something that seems tantalizing, and many of us will merely redouble our efforts to learn what the big secret is. No matter how obsessive we might be, we all feel a bit of resentment at being excluded from a secret, and are pleased if and when we find out what the hoopla's all about. Men tend to be more driven than women, but people of both genders are tantalized to varying degrees by this Big Secret. Our society's Puritanical attitudes compound the frustration by making anything sexual into a taboo subject.