While we all try to figure out why so many people write blogs, one possible explanation is: it might be good for us. For example, it's generally accepted that there's a large group of homemakers – mostly young, single parents – for whom email and blogs are the primary opportunity to be a thoughtful grownup and have serious discussions.
And here's another way blogging can be good – taking the time to express something carefully can help us to understand our own lives better. I'm thinking, for example, of an entry I wrote in this blog over a year ago. I was expressing an idea I'd had for awhile, but I gave it a clear description and a handy name, and now, when life's minutia start to drown me, I'm often able to relax and remind myself, “It's just a Pipeline.”