Why Use Twitter for Internet Marketing?

Oh my Gosh! I spent way too much time playing around on Twitter. For some reason everyone in IM Tweets. I don't get it! Yes, I understand that it is a good advertising medium. But, I really don't see how.... It's definitely not targeted traffic. I mean you're sending your tweets mostly to people who don't care. Also, I don't read half the tweets I get, even if it's something I'm interested in.. Like IM. Anyway, it just seems to me that people are concerned more about how many people are following them or how many people they follow? So, I guess only time will tell? Can someone out there tell me why Twitter is so important?

P.S. Oh, Follow me on Twitter! Lol!