They're middle-suckers, trying to get a slice of your silver.
They say "free wordpress blog" - don't you know wordpress itself offer the same service? The difference? Wordpress is owned by wordpress.. Get what I mean?
So why don't you go straight to wordpress.com and signup for their free blog offer (if you really like wordpress - blogger 'blogspot' is an alternative). If in case you don't like the idea of subdomains like yourblogname.wordpress.com or somethinglikethis.blogspot.com, wordpress and blogspot do offer a service where in you can use your domain (yourdomain.com) to represent your free blog from them.
So, what's with the idea? Simple, you only pay for the domain (yourdomain.com) per year. What about hosting? No cost! Again, wordpress and blogspot do offer free blogs.
So that is, paid domain + free hosted blog (wordpress or blogspot) = less expenses - since you only have to pay for the domain. Compared to, paid domain + paid hosting service (justhost, 1and1, godaddy) = more expensive - since you pay for the domain, the hosting, and other additional charges..