This is a question I used to struggle with. Twitter is so boring and dull, why does everyone need one? Why do people care what I am doing? Two answer both those questions: 1. Not everyone needs one. For example the people who Tweet their lives. "Just woke up... went to bathroom..." No one cares. 2. People don't care what I'm doing... sometimes.
To further explain, Twitter is essential for anybody trying to be a somebody. Look at celebrity Twitters, they have millions of followers. Why? Because people care about famous people. Everyone wants to be involved in someone else's business, and we all put it out there anyway.
So who needs a Twitter? If you are a journalist, writer, musician, painter, w.e.- Twitter can be something that jump starts your career. If you start to build a following, and people start spreading your Twitter, you may have caught fire. It is the perfect quick and easy way to plug your work whether it be article or new song. Just post a link, and say "check it out".
I thought Twitter was something to annoy me throughout the day seeing all these crazy good-for-nothing statuses, but now I see it as something better. I Tweet every article and Blog I write. I Tweet my band, and follow other people from Staten Island. My hope is that they check out the page, like what they see and follow back. Ultimately that is a quick and easy way to network. It's a link to your catalog of works, or links to something you have in common with your followers. It's a powerful tool if you use it wisely. Give it a shot.
Follow my band -http://twitter.com/POF_Band
Follow me- http://twitter.com/JSarachik_POF