Content locusts are the fault of the games themselves, not the players. There is a reason we're seeing a lot more sandbox gameplay oriented titles in the pipeline. A constant stream of railroad content is nearly impossible to do, unless you implement massive grinds. You can cheat by using time-gated content (this is the method that FFXIV utilizes; GW2 does partially as well), but it's no substitute for real player-driven content. This is also why roleplayers tend to be the longest subscribers to games like this - they make their own game, so to speak.