There's a great article on blogs - right here on Blogger.com. The article talks about, among other things, why blogs are a good communication device. Here's a snippet:
1. Diversity of opinion - That's a no-brainer. Bloggers publish hundreds of thousands of posts daily, each one charged with its author's unique opinion.
2. Independence of members - Except for your friends saying "You've got to blog about that!" bloggers are not controlled by anyone else.
3. Decentralization - There is no central authority in the blogosphere; publish your blog anywhere you want with any tool you want.
4. A method for aggregating opinions - Blog feeds make aggregation a snap and there is no shortage of services that take advantage of that fact.
Check out the full article here.