This blog is mainly some kind of diary for the game's progress. I will definitely go through several PC changes withing the next few decades so I think it is safer to store that kind of information on the net than on some random .txt file.
Second, I want to see how interested people are. Do they like the ideas or are they total crap? Can they provide useful feedback, help developing the game or will the site only be visited by google bots and spammers?
The idea of putting up a blog before a game even exists is not new. Still, I think it is one of the best approaches one can do to prevent single-minded decisions.
Eventually, when the game gets playable in the early stages, I will release source code bits and maybe set it up here as a in-browser runnable application (which is a very easy with Java). Until that, I will write on the concepts, ideas and features, release screenshots and maybe tile designs. (YES I want to make it a graphical roguelike)