I vote that we stop dismissing Twitter just because the majority of people who are joining its ranks are there to be social. We like the fact that humans are social. It's good for society. And what they're doing online is fundamentally a mix of social grooming and maintaining peripheral social awareness. They want to know what the people around them are thinking and doing and feeling, even when co-presence isn't viable. They want to share their state of mind and status so that others who care about them feel connected. It's a back-and-forth that makes sense if only we didn't look down at it from outer space. Of course it looks alien. Walk into any typical social encounter between people you don't know and it's bound to look a wee bit alien, especially if those people are demographically different than you.
Twitter and I have managed to work through our issues by maintaining rigorous control over who we follow, and thus far it's all to the good. But—far more important—I learned a new word today!
phatic adj. Of, relating to, or being speech used to share feelings or to establish a mood of sociability rather than to communicate information or ideas; e.g., hello or how are you?