I agree with P in that it is unfair to dismiss online discoursed entirely, and with Josh that it is appropriate in specific situations, but I feel online conversations are for the young. The Internet is an easy way to express yourself. You can take the risks you normally wouldn't, because you're simply not standing in front of the person. The communication that occurs over the Internet is free of stress caused by talking face to face.
Morningstar and Farmer suggest, through Habitat's structure, that in a virtual world people seek "richness, complexity and depth," but at the same time their goal for communication between machines is "to take place primarily at the behavioral level (what is there rather that what it looks like)." That seems to be a complete contradiction. Consider that the Internet cannot be complex and work primarily at a behavioral level. That is not possible.
However, I feel the behavioral level they suggest is very accurate to the current status of the Internet. And I feel that is why the Internet is so successful in the pre-teen/teen ages. As you get older the world becomes more complicated as you learn, question and experience more. As I get older I consider all of the ways I analyze my life, and my future. But when I was younger everything was a lot easier to explain, happy or sad, good or bad, mean or nice. Simplicity fades as you get older, and in many ways I feel the Internet is trapped in the simplistic stage describing things by functional models rather than physical or emotional expressions.
I feel that as you get older you begin to out-grow the Internet. Checking email used to be fun because it was exciting letters from friends or fun forwards. Now forwards clog your school email, and emails are from professors or group project members reminding you of all the work that must get done. IM used to be a social event with all of your friends, now its difficult to find anything in common with some of your best high school friends and IMs tend to be forced conversations that you can't wait to end. As you get older the Internet becomes less of a toy like it was in your youth, and becomes more of a tool. At least that's what happened for me.