Criteria for a Good D&D Setting

I'm always kicking around these "elevator pitches" in my head for some upcoming D&D setting.  I develop bas cases of the Gamer Attention Deficit Disorder… ideas accumulate in the back of my brain like flotsam and jetsam.  Just to get them out of there and put them down on paper, I created a section of the blog, The Junkyard, just for dumping ideas (hopefully, it becomes my place to go scavenge for ideas in the future).  Like the man said, an idea is the most resilient parasite - it's impossible to eradicate - but maybe you can park it somewhere to cool off.

One of the problems with these half-baked settings mash-ups is that once you take them out and really look at them, half the time I realize they're not really good fits for a D&D campaign after all.  Which kind of begs the question, What are the criteria for a good D&D setting?

You would think that some hoary elder of the D&D blogosphere would have established the definitive criteria for the ideal D&D setting some time ago, but alas, I cannot seem to recall seeing such a list.  Don't get your hopes up for seeing one here.

The problem is this:  Dungeons & Dragons is a game, with elements that appeal on the level of a game.  It also generates fantastic stories.  I'm not a story-oriented DM; my D&D style is to throw stuff on the table, play the game, and the story is what you have after all the game elements come together after a night of play.  But somewhere along the line, a lot of us started treating D&D more like an emulation of fantasy literature, and less like a game that had some fantasy inspirations.

The problem of designing a good campaign setting requires coming to terms with the game-oriented elements of D&D, and making sure they work in the context of the setting.  Many times, house rules and similar changes are foisted on the game to minimize or remove game elements that are perceived to get in the way of the fiction.  Sometimes these changes to D&D are only cosmetic, but other times they're major surgerry.

Let's start with the perspective that D&D is Always Right.  If that's true, what are the core game elements that need to be accounted for in the setting?

Here's the list I have so far:

Dungeons
Let's face it, a D&D world is crawling with these underworld locations filled with traps, weird magic "specials", monsters, and lots and lots of loot.  Ideally, the setting should support a mega dungeon concept, too.  Where'd they come from?

Classes and Levels
The D&D world is one where there are clear demarcations between different approaches to adventuring, as embodied by the four base classes, and where experienced characters and rulers wield vast power compared to their zero-level brethren.

Alignment
Powerful and far-reaching game effects are keyed off whether someone is good or evil, or at a minimum, Lawful or Chaotic.

High Magic
The D&D world is one where folks with the requisite intelligence (and perhaps money) can study magic, learn to fly around, and toss fireballs.  You can come back from the dead, too, if you know a high level cleric with a good wisdom.

Humanoids and Monsters
The wilds are crawling with talking, anthropomorphic furries that want to eat people.  Just where do all those humanoids and monsters come from?

XP for Gold
The whole paradigm of gold = experience means there's likely an "adventurer class" in society that specializes in exploring old ruins, and successful adventurers can amass fortunes in wealth.  Which brings me to my next point...

The End Game
Default D&D assumes an end-game where high level characters can take their vast fortunes and carve out small kingdoms with their many followers.  This implies a degree of wilderness or borderland, ideally in the form of a hex crawl.

Demi-Humans
Characters in the D&D world rub shoulders with these curious pseudo-humans with pointy ears and funny accents that live in the woods or the hills.

Added:
Clerical Magic
The default D&D setting assumes clerics gain their powers from deities, which implies quite a bit about the nature of the cosmology and humanity.

Vancian Magic
Spell books, spell memorization, and flashy combat magic create a set of expectations about the world and how arcane magic functions.

Please suggest more to add to the list if there's some I missed.

My goal is to have a small checklist of things to address when I'm kicking around alternative campaign ideas.   It'll help keep my ideas grounded, or at least ensure I'm addressing core elements of the game or developing suitable equivalents.