The biggest reason is probably that we have a dedicated server (which means that it is just the Wildfire Games content on that server, we don't have to compete with a lot of other sites). This does cost a bit more, but it does give us a lot of freedom and capabilities. Both in that we can do things like have it host some automated tools for the development (I'll leave it to those who knows more about that to explain it in more detail), and use it to host the downloads ourselves (and don't have to rely on other sites like SourceForge). And of course that the web site and forums takes less time to load and interact with which is nice for everyone who uses it. We could probably have gotten it a little bit cheaper, but as with most things: you get what you pay for.