If you aren't with a publisher who promotes your work, then anything you do to keep your name and work visible is a must. Prior to blogging, I sent out a monthly newsletter to keep touch and personally promote myself, so when Blogger came along and allowed me to set up a site where I could personally interact with other authors and portential fans, I took advantage of setting up Dishin' It Out. Since I also write Western Historical Romance, I set up Cowboy Kisses and invited thirteen other western authors to participate on assigned days. We are not just a promotional site on Cowboy Kisses or Dishin it Out. On Cowboy Kisses, we tie our work in with the research we do and things we've learned. On Dishin' It out, I offer the opportunity to fellow authors to promote themselves, use an RSS feed to assure the blog travels as far as possible, and share each daily post. My partner, Rita Karnopp, writes some really amazing writing-related blogs. I also take advantage of invitations from friends to blog on their sites because doing that gives me a whole new audience, a few of who might decide to visit me.
In my opinion, not having a blog limits your ability to move up higher on search engines and prevents readers from learning more about you as a person.
Just my two cents worth.