Fellow Iron Heroes maven though I may be, I'll have to disagree with the OP on this one... or rather, suggest that the narrative he's detailing might need some refining.
IMHO, there are really only two reasons why D&D 3e might seem to suggest a particular fantasy subgenre now as opposed to in previous editions:
1) Previous editions were more open-ended than 3e about certain concepts like balance between classes, the effect of a mix of classes on successful completion of encounters, and especially the availability, means of creation, and suggested distribution of magic items. In reality, it's no easier or more difficult to play a gritty Thieves' World style game, a pseudo-historical Vikings game, or a classical-period God of War pastiche game in 3e than in any previous edition; it's just that there actually are play balance issues related to changing the rules that are enumerated in the books now. The basic system engine is clearly capable of being adapted to low-magic or different-genre games; witness Midnight, IH, Grim Tales, etc etc etc. The kicker is that designers take the changes required to effect lower magic into the mechanics themselves. 1e and 2e included no rules or guidelines as to how to run an encounter differently for a party of four characters with a few potions and a +1 item or two as opposed to a party with a fighter clad in +5 plate mail with the feared hammer/girdle/gauntlets combination. 3e does. That seems like a feature rather than a genre-informing "bug" to me; if you know the mechanical effect ascribed to something, it's easier to tinker with it.
2) D&D designers have created settings like Eberron and Ptolus in which a logical extrapolation of D&D informs the flavor and nature of the game world itself. This is something that has been discussed at long length from the halcyon days of Arduin and early 1e; I've read letters by several gamers who created wacky magitech-ish worlds featuring cleric-run hospitals, magical streetlights, teleport-pad cargo transports, etc., and I've been in a few games with this sort of flavor. However, the potential for magic to transform a setting was simply ignored or worked around for much of the history of the game by setting designers, who clearly wanted to fit a squarish but round-looking peg (D&D, a game ostensibly designed for high-fantasy/sword-and-sorcery roleplaying but sometimes fitting a superhero-level genre) into a thoroughly round hole (the classic fantasy world).
I don't really think that this signals a departure in how D&D actually gets played; as Psion mentioned, demographics are in the hands of the DM, as (really speaking) are magic and magic items; there is a reason those are called guidelines. The nice thing about this sort of discussion, however (and perhaps the nice thing about 3e, having made this transparent) is that we can talk specifically and explicitly about how to make D&D conform better to the genres we like, should those genres involve changing base assumptions of the game system. Hence the approach behind, say, Iron Heroes.
Incidentally, I'd disagree that 3e has somehow raised the power bar; if anything, the PHB and DMG pretty explicitly spell out the fact that members of PC classes are exceptional individuals, and 3e does well by introducing a comprehensive set of NPC classes. The demographics also help to keep high-level PC-class folks pretty uncommon. In fact, if anything, 3e has afforded some setting designers (cough *FR* cough) the opportunity to tone down some of the NPC power in existing settings.
![:]](http://www.enworld.org/forum/images/smilies/devious.png "Devious :]")
