None of what has been said so far has been incorrect, but none of it has been fully correct either.
It is true that it is quite easy to find yourself using the internet in such a way that your time is used inefficiently. This week my wireless modem burnt itself out and I was left internetless for 2 days. It was a weird feeling, like a prolonged power outage without any alternate sources of light. But I found that in that 2 days I had more time on my hands than I've had in months. I don't have time for television anymore these days, I used to watch reruns and new episodes of shows, but now I only really keep up with the Daily Show (usually several days after the fact) and 30 Rock, and the rest of my idle time is spent on the internet, several hours a day, at least 3 if you count the idle time spent at work.
Is that a waste of time? Some of it probably is, but it's no more of a waste of time than most everything else. Thinking in terms of opportunity cost, very little of what you do on any given day isn't wasted. It's certainly easy to think that internet time is particularly wasteful, but I think that's because it's spent sitting and staring, it looks useless. But when I'm here or on my other forums or on meebo or whatever it's just like attending a town meeting, or talking on the phone, or writing letters to people, or reading a newspaper, or taking a free class on the underground music scenes of the 60s/70s/80s/90s/00s.
We don't have much of a historical reference for this sort of thing, outside of a rather small community of venerable geeks the internet has only been a resource to people for the last 10, maybe 15 years. Can we really say with any certainty that the relationships we form out here are somehow less valuable than the ones we form in meatlife? I mean, I've gotten to know and broken contact with dozens of people on the internet over my time on the interscape. But I've gotten to know and broken contact with many dozens more in my meatlife. I do think that some of the people I've met will be friends with me for quite a long time, maybe for decades into the future. We read about people in the past having these relationships via post and that seems romantic and meaningful to us, how is this any different, really? It means something, it matters.
Think of internet dating. Many people reading this have met significant others via the internet. Have these relationships been any different than relationships formed through other means? There's this weird, not-entirely-rational stigma that attaches itself to internet friendships/relationships, like meeting somebody in a fuckin' bar is more legitimate than meeting somebody in a music forum. So, we can maybe make a blanket generalization that people who spend a lot of time on the internet are more awkward in meatlife. There's a lot of self-hatred in this, we kick ourselves because we weren't jocks in high school and we don't coast through the social landscape effortlessly. Why shy away from this resource?
Fuck that, embrace the internet. What would you do without the internet? Where would you be? Do you honestly think you'd be happier? Would you join a fuckin' fraternity or sorority and make friends that way? Join the gaming group at the local comic shop? Or would you be miserable and sullen all the time? Honestly I think if more people got over this self-consciousness they'd be a lot more content with their lot.
tl;dr I think all this bellyaching over the appropriateness of internet use is really about self-denial.