Willing to clutch? There are not a lot of studios (some might argue none) that have delivered on the amount of content needed or desired, and that's been true across nearly every MMO ever made...
That would be wonderful, except that no one has ever been able to spit out that much content (and been able to keep their proverbial head above water that is). EQ was renowned for putting out half finished shitty content and while I think that EQ2 did well early on, they really phoned it in over the last few years and many of their "dungeons" shouldn't even be counted. On top of that you have the issue of people progressing as fast as humanly possible to the "endgame" of available content, such that:
So out of the 82 dungeons
I just counted for VG, they were kind enough to bold the 11 or so
"most commonly run"dungeons and nearly half of those are 50+ (if you toss Rahz Inkur in there for being 47-50). Point being, if you want to forgo instancing you're going to have to include a LOT of dungeons and zones, as once your playerbase churns through your lower level content they're going to be stuck with 5-10 dungeons (10 being generous, many have less) that they will have to run over and over again. You could say that a system w/o levels might mitigate that to some degree but people will always try to progress towards the best rewarding dungeons, and any honest attempt to create enough content so that your population is spread out enough to do away with instancing (and not create hundreds of low pop servers) will likely end in failure. As much as we hated on SOE in EQ1 for the lies, timesinks and bullshit, they were being honest in that they couldn't keep ahead of players...