If you pay attention to someone’s tweets, you’ll learn an awful lot about them. Your mind hoards all these little facts, like where they get their coffee, what they thought of a film, and what they like doing.
Sadly, you no longer need to ask questions. Facebook has the same problem.
As Cennydd put it:

Apart from killing small talk, I’m tempted to delete my Twitter account for how much time I spend reading my feed when I could be reading—oh, I don’t know—Ulysses. Or about the Israeli-Palestinian conflict that I’d been ignorant about for so long. But I’m keeping Twitter around, for now.
Why I haven’t deleted my Twitter account yet.
Fear of Being Out of Touch
I’m frightened by the idea of not knowing what people are talking about. I realise this is an irrational fear, and I’ll still know what’s important from reading blogs. I realise I can simply subscribe to tweets without posting, but that’s out of the question, too; the urge to respond to a tweet, or update my followers with the latest disaster exploits of my new kittens, is astonishingly powerful.
The Need for Ambient Intimacy
Twitter’s a bit of a weird medium. Intimate, yet cold. There is a wall between you and your followers. There is no guarantee anyone following you will remain a follower: they’re fickle and will unfollow you if you post something annoying. In addition to that, even if they’re apparently following you, there’s no guarantee that someone’s even listening to your updates—maybe they’re following 20,000 people. Maybe you’re not on their priority list in TweetDeck.
I follow 188 accounts, some people, some RSS feeds, and I read all of them. I use it to stay in touch with my close friends, but I also have lots of acquaintances (but not BFFs) I want to stay in touch with. Twitter’s the perfect medium for it. This is not unrelated to the other reason I don’t delete my Twitter account: fear.
So I’m sticking around for now. Grudgingly.
I’ve adopted the philosophy that I’ll keep much in my life mysterious, unpublished on Twitter. There’s stuff you can only discover if you ask me questions, and even then, I may not answer. But at least it’ll be a semblance of a conversation, right? Plus, I’ll need to keep some stuff for my autobiography.
The other thing I resent Twitter for is how self-conscious I’ve become about writing. I apparently have several hundred people following my updates, with maybe 20% of them who are actually humanoid. And perhaps only half of the humanoid followers are actually listening. Even so, the number makes me anxious—and I resent that I care what listeners think about what I’m tweeting about lunch.