The internet is like a parallel universe based around the exact opposite rules. You can look at whatever you want, talk to whoever you want, say whatever you want, do whatever you want, and no one is going to stop you. There is no wonder that so many suburban children become "internet addicts" these days, given that it is the sole element of freedom in their lives.
And Minecraft is the ultimate embodiment of this freedom. There is no structure or goal to it, just the freedom to wander about a crude approximation of the natural world, go on adventures by yourself or with friends, and build things with your own two hands. In short, it is a safe, sterilized version of the ancient childhood experience of wandering the woods, building forts, and carving out a society secret from the adults. It is the solution to problems we created ourselves out of fear of the world.