Its different because its not just going to be the producer talking but developer heads and not all the head developers have a forum handle to talk, not to mention its on the FFXIV promotional site complete with RSS feed so the potential subscriber base is a lot bigger. My guess is they plan to use the blog as a venue to talk about new and upcoming content without needing to use the Official forums and without using the producer letter which is well... a producer/director only thing. Furthermore at some juncture they plan to shut down the current official forums and merge it into the new ARR one so who knows what posts might get lost in the shuffle, its better for new promotional material to be on the official site.