This would be interesting to discuss. I can think of how some of that influenced why 4e didn't work for me, but I'm not sure how much of it (even if we're limiting it to mechanics rather than fluff).
You're right that I'm not talking about the character of the fiction per se. The basic fictional elements in 4e are pretty familiar within the D&D corpus (warriors, wizards, healing-and-fighting clerics, kobolds, orcs, demonas, gelationous cubes, etc, etc).
The "shape" of the fiction (not a very precise word, sorry) I think falls recognisably within the D&D corpus, but is not necessarily typical (depending on what one treats as the paradigm). For instance, the sort of game that Gygax describes in the closing pages of his PHB (under the heading Successful Adventures) and in the opening pages of his DMG (where he talks about how it might be permissible to suspend wandering mosnter checks in some circumstance) will tend to produce a fiction in which planning, caution, careful exploration (in the literal sense of that word), rationing of resources, etc figure prominently. I don't play Torchbearer, but of contemporary RPGs I think it is one that aims directly at producing this sort of fiction.
Whereas 4e I think will tend to produce fiction that involves drama, frequent (and frequently successful) heroic effort, and characters who are more focused on the "now" than on the "we'd better carefully check what's behind that door". I don't know many D&D novels - only the early DL ones - but I think the shape of 4e's fiction is closer to that than to the fiction that Gygaxian dungeon crawling will tend to produce.
I would say that the
reason for that difference in fiction goes back to the difference in play procedure/focus and associated mechanics that I've pointed to: 4e treats the encounter - that is, the chalenging situation that demands a resolution - as the basic unit of play. Exploration (in the not-strictly-literal-and-more-technical-sense) is a means to an end, rather than an end in itself. To borrow (and hopefully not mangle too badly) some phrasing from
@Charlaquin, in exploration play,
and in Gygaxian play, encounters are things that hold up your exploration (in Gygaxian play that get in the way of your looting, which is the point of exploration in that version of the game).
Whereas in 4e encounters are the crux of the game. To quote the back of the 4e PHB,
The world needs heroes! Heroes are people who overcome challenges and resolve crises.
And in the context of a RPG, if you want the focus of play to be on
resolution, then you have obliged yourself to come up with mechanics that will enable that. Which (in muy view) underpins all the more detailed minutiae of the 4e action resolution systems.
That's not to say that 4e is perfecly coherent - upthread I've already pointed to its muddled terminology, and it's littered with legacy aspects that push in the opposite direction to its general thrust (eg the presence of Thieves Tools on the equipment list, which makes prep and planning matter in that domain at least).
Still, I think the general thrust is evident, starting from those words "Between encounters, your characters explore the world."