They don't change ARR areas because the future is their priority. They aren't wizards; they can't do every little thing the players want, so the future is what they choose to focus their efforts on. Why? Because the future patch content is where the profit lies.

Standard player behaviour is to login to any game that has a patch released, complete the patch content over a few days, then move onto the next game that just had a patch release. This is how they draw players back to the game, after which they have to find ways to keep as many of them sucked in as they can for as long as they can. That's how they keep the game alive and how they keep it highly profitable.