I agree with what most everyone has said, and I too have been hit by the "you're now at an enemy base" hammer. It does bite, but I get over it. I can't imagine it being very difficult to not have the base ownership change until the map changes and the server resets the arena. I mean, we're not even getting the same map after the reset, so what's the point in changing ownership at that moment?
From what I hear, once the map is won, ownership changes to what it will be the next time that map is used in the rotation. If that's true, then why do it the instant the map is won?