Colin Johanson, Lead Content Designer for Guild Wars 2, has just posted an update to the ArenaNet blog. In it, he discusses some of the company's philosophy regarding measuring the success of Guild Wars 2 and how best to achieve that success. A big part of that philosophy is to constantly evaluate how fun the game is and whether that fun makes the content compelling enough to stand on its own.
To that end, he relates that the fairly standard gear treadmill has been more or less removed from the game. While there is item progression through levels, rare items are made desirable by visual, not statistical, distinction. Dungeons, rather than having a tiny chance of dropping high-demand items, reward players with tokens that can be traded for items. Within those dungeons, variations have been made possible so that players can choose different routes to explore rather than be forced to do the same exact run again and again.