The more things change, the more they stay the same.
If you look at the history of technology, particularly any new technology that arises to facilitate interpersonal communication, you see the same patterns over and over. As a society, we just "forget" these patterns. And as such, we are doomed to repeat them.
If you look at the popular press around the time of the invention of the telephone, there was an uproar about how "depersonalizing" this new technology was. Cries of: "It will destroy relationships!" "There is no way to have an exchange of emotional depth over this infernal contraption!" "It will isolate us!" "It will turn us into machines!"
Even before the telephone. Look at the invention of cheap printing. There were actually outcries about how people would become "unhealthily absorbed" in reading novels, taking in the fantasies and ideas of anyone willing to write them down. I'm dead serious. The literature is out there, just a bit buried in the mists of the past.
Fast forward to the beginning of the Internet and the web/email. Same cries of concern. "It will isolate us!" "It will dehumanize us!" "It's an unhealthy pursuit!" Ad infinitum.
Second Life is not a game (i.e., no pre-defined "artificial" goals like MMOGs). It is a means of creative expression, focusing on interpersonal communication. You interact with people by what you create and what people see. You talk to people. You form ties, both strong and weak, with other people...and expand your social network.
In my mind, SL is no different from any other new interpersonal communication technology. Historically, most people never "get" these new technologies when they arise. But the early adopters do. They embrace it, and use these technologies as "extensions of Man" (to quote McLuhan). Eventually, the rest of society "gets it," but most of the time only after a generational change.
Read "Natural-Born Cyborgs: Minds, Technologies, and the Future of Human Intelligence" by Andy Clark for more insights into how humans have always sought and embraced technological extensions. Starting way back at "the axe."
Anyway, I fear I am ranting. But this "pattern" of people initially trivializing and even fearing a new interpersonal communication technology is nothing new. What has come before will come again.
A generation from now, the idea of using virtual worlds like SL for meaningful interpersonal communication will seem as natural as the telephone is today.
You can quote me on it.

-John