The parent comment is not insightful.Twitter can be all the inane things the parent describes. Just like small talk can be inane, launching and goofing around can be inane, and school kid chatter is inane. But that is only one use of Twitter.
I work from home and I am relatively secluded during my work day. I am not a social butterfly by any means, but I like to talk and socialize to take a small break. Twitter gives me the opportunity to have those quick social interactions during my work-day.
I am also an in a field where there are a lot of others in the same or similar fields on Twitter. I get professional benefit from following them and, hopefully, them following me (thought I don't subscribe to quid pro quo following. If I find you interesting, I will follow you.) I am able to ask and answer questions, be alerted by events relevant to my job, and generally share outwardly. Not all the chatter is professionally focused, but enough is that it is worth while.
Twitter is a tool that unlike the IRC is open enough that you can more or less control how much stuff is sent to you by following folks and is closed enough that you can really limit the spam you receive. In fact, I rarely, if ever, get a spam Tweet. The trick to make Twitter successful for you is to build a network that is relevant to you. I don't view my follow or following count as a contest (thought others do). I view it from a quality stand point. I have far more followers than I follow. Frankly, I don't know why some of my followers follow me (and I don't mean spam bots, either).
If, however, you focus on the numbers, then you become innundated with spam and other bad behavior.