B/C supermods can do as they please. They decided to combine the two Mazda5 gens into one forum without Mz5 member input (though consensus was leaning towards that anyway). (yes)
Based on a quick look around, it seems like a common structure change applicable to all sub-forums. I'm guessing it is b/c the top level post are disorganized and all post should really be categorized so that it can be more easily referenced -just my guess.