D20 sweet spot (was White Sucks, Fighters nice things, etc.)

[FatR]

Has anyone even made a fantasy world with superhero level characters that isn't shit?

I believe Brandon Sanderson's worlds are decent.

Of course, they tend to be horrible places to actually live in.

Of course, no fantasy world, whether it has superhero level characters or not, can stand to an extended scrutiny. Worlds that stick to quasi-realism simply are better at creating an illusion of verissimilitude. But ASoIaF's world explodes as thoroughly as Slayers' world if you try to analyze it.

Marvel and DC both pretend that their respective supeer-smart heroes haven't converted the world into a post-scarcity utopia by flat out ignoring the issue.

A post-scarcity world is almost certain to be a self-eliminating distopia, and anyway the much more likely outcome in both Marvel and DC universes is neo-feudalism in vein of the Justice Lords. It only doesn't happen in main timelines because of ironclad editorial demands.

I suspect a large part of the problem is that massive power disparities between the masses and the chosen powered people are inherently difficult to handle.

Most of our world operated on the basis of power disparities between the masses and the elites since the dawn of history. Heroic fiction by definition involves people who are Just Better than the rest of the crowd. Escalating these concepts is really only difficult to handle in the sense that doing so it leads to setting features from which many modern writers will recoil.

The difficulty is not in disparities between heroes and masses. It is the disparities between heroes (which is what you're talking about in the rest of your post). As the range of power levels grow wider, and power diversity increases, the probability of introducing a power or a combination of such that just shits all over everyone else in the setting or allows to bypass wide swathes of possible adventures grows higher.

[FatR]

No, the problem is not that world changing abilities were given to the Wizards. The problem is that the DMG doesn't have a chapter about using world changing abilities to progress the world. And the other problem of course is that the non-casters don't have world changing abilities. Even though simple management and leadership could easily change the world considerably more than magical creation shenanigans.

-Username17

The problem of wealth of the land in DnD is a two-pronged fork:

(1)Either rulership and tinkering with the infrastructure to make the land that you rule wealthier significantly improves your personal asskicking ability. In which case it is highly likely to break the game. At least it does so in the official rules of 3.X. And it is going to make raiding dungeons and stealing from dragons a questionable choice of career.

(2)Or it doesn't. In which cases investing into development of your lands is absolutely irrelevant, if not actively detrimental, to your chances of fighting off a next dragon or evil wizard who comes knocking, so any "progress" is not self-sustaining - it does not provide a society significant survival advantages by itself and depends on benevolence of rulers. That's the situation in the Tome rules.

[Schleiermacher]

As presented that doesn't seem like much of a problem.

2a (Irrelevant but not detrimental) seems like clearly the best option there, both in terms of game incentives and desired setting assumptions.

Evil monsters kicking society in the face on a generational basis seems like a very good explanation for medieval stasis, and has the handy side effect of supplying heroic PCs with a constant stream of things to fight for and against.

Rulership is its own reward, and "tinkering with infrastructure" is somethng that people will still do even if it doesn't help them delve dungeons, because it helps them spread their rule, or extract more wealth from their domains, or improve the lives of their subjects, and/or pretty much anything else a ruler would want to do, depending on personal inclinations.

[Mechalich]

The difficulty is not in disparities between heroes and masses. It is the disparities between heroes (which is what you're talking about in the rest of your post). As the range of power levels grow wider, and power diversity increases, the probability of introducing a power or a combination of such that just shits all over everyone else in the setting or allows to bypass wide swathes of possible adventures grows higher.

You're right, disparities between the heroes. Looking at it, I think I phrased it that way because super-hero worlds are forever attempting to include people who are just 'really good' members of the masses as lower tier heroes, and often allowing them to embarrass actual heroic characters with real powers for plot-related reasons (looking at you Batman).

And I think the probability of inducing a setting-destroying power rises very quickly indeed. At least if your setting is intended to be stable over the long term. Admittedly it may not be. If you're playing Wheel of Time d20 then effectively all campaigns happen with in about a five year window and the fact that life is completely different within a generation after the last battle and an industrial revolution has occurred (and Sanderson totally teased that in the books) is meaningless. But most settings designed to be used for RPGs won't be built that way because it doesn't support the business model of endless books for ever.