Sammael said:
Epic levels are a built-in core assumption for most settings (Greyhawk and FR being the most prominent) and have always been there (albeit they weren't called "epic" or another fancy name). Even Eberron has epic-level Lords of Dust (see recent Dragon magazine) despite its overall lower-level NPCs. Now, if three core worlds support epic play, I think that we can safely say the epic play is not really optional (as far as official materials go).
DMs are, of course, free to set the cap as low (or as high) as they desire. I am in favor of natural caps - keep playing as long as the game is fun.
Greyhawk is, outside of piazo's magazines perhaps, which, while officaial, don't define the baselines or core assumptions of the game, a dead setting, in the sense that it no longer baseline for the standarts of D&D.
FR has always been the high power setting, with 3rd edition more than ever. You'll find an awfull lot of people that agree that NPC's such as Elminster are cheesy for them and it's also notable that all those PC's and their role in the world would still work where they level 17-20. Netheril would really be the only thing that wouldn't work without epic rules and that only because epic rules, in part, have been made to accomodate it. It's also hard to deny that FR is in any way still the base setting for D&D.
For the Lords of Dust, well, they are again from dragon, not wotc. And the Delkyr are all CR 20+. Not exactly right to accomodate epic levels, but just right to be the "final monster" to a campaign that ends at lvl 20. You could say that written up epic challenges for eberron doesn't exactly proves that eberron supports epic level play, but instead epic level play in it has to be supported from an outside source to even be viable.
Of course, I never even denied that epic level play currently is part of the core assumptions, just that it shouldn't be. With the advent of 3rd edition D&D was to be build in a modular way that is founded on one set of core assumptions found in the core rulebooks.
That these core assumptions could be broken up by the existance of an epic ruleset outside of the core rules that now has to be taken into consideration with every new release defeats that whole concept to me.
As a small aside, looking over the whole of my planescape collection about everything caps around level 20. Oh, and while I'm not exactly a grandmaster of evaluating 2nd ed power levels and they where certainly controversial in their time as well, the stats of Grazzt and Pazurael seem about right for a 20th level party as well. Since this is a discussion relating to the same subjects planescape took on and you brought up setting I thought it worth mentioning.
