I've made a point of running every dungeon (apart from Qarn and AV, because ugh, not fun in DF) at each level tier to ensure that I'm figuring out the best way to play my class in a true group environment. In 2.1 the XP will be raised to a point to where it should trump that of FATEs, assuming you're not waiting 30 minutes for a party, (which shouldn't be an issue for a tank) so there will be more incentive to do dungeons. That's not to say that some people won't still pick the path of least resistance and continue to spam that same 1 button to 50 though.