personally, i think its very boring to go to same routes all the time, and i have been thinking about this, maybe you could add a place that people can unlock after doing some sort of quest or goals, where you can find better stuff there, maybe you know, more rares and legends and UB's. And to top it of, it should be quite big so that people could explore it.
(im not sure if this idea has ever been submitted, so please tell me if it is)