Or they could simply add a function that tracks whether or not a player has taken an action in the past X minutes. If X minutes exceeds a limit (10 minutes or so?) the games automatically boots the player from the world. There are a handful of other games that ALREADY do this so I doubt it would be hard to implement.

Rolling restarts would put a large amount of stress on the log-in servers as those people booted off will instantly try to get back on.