OK, so that good point I mentioned at the end of the first part comes in sections three and four of Ted Gioia's essay, in which he contrasts the stylistic experimentation of Joyce and Pound and Faulkner with the subject-matter experimentation of (unnamed) sci-fi and fantasy writers of the same period. Though he makes the somewhat questionable assertion that the latter were significantly more commercially successful than the former, the point is interesting, and one I hadn't particularly considered before; namely, that the sci-fi writers are just as experimental as the stylistic innovators, but that, as Gioia puts it, "they did not experiment with sentences, but rather with the possible worlds that these sentences described." He also seems correct that the sci-fi (I feel no need to use "conceptual fiction") mold of experimentation won out over the formerly literary type, as he points to examples like McCarthey and Saramago and Rushdie and Chabon and so forth (mentioning Paul Auster, incidentally, before trashing the mystery genre, which is inexplicable to me) as the new literary elite, inspired more by sci-fi's innovations than Joyce's.
I'm not sure I understand, though, why these two strains need to be placed in opposition. For one thing, not everyone falls firmly on one side or the other: Pynchon comes to mind; Saramago and Auster are other examples Gioia himself mentions but seems to unwittingly discount in these terms. For another thing, stylistic experimentation in "realistic" narrative is every bit as much a Houellebecqian rejection of the terms of the actual real world as is reality experimentation in traditionally styled narrative. The two are complementary.
The works of art I tend to respond to most strongly are those that in one way or another reject the world-as-it-is. Because the world-as-it-is is, to me, unacceptable, and by rejecting it we demand that it change (regardless of whether that change is possible or even definable). I can't exactly define the general form of this rejection, but I recognize it when I see it, and it's why I tend to lump a lot of non-sci-fi works in with sci-fi in my mind's conception of the genre, works like (and these are the first examples that pop into my head, from different media) Kubrick's Eyes Wide Shut and Celine's Journey to the End of the Night and Arrested Development and the early music of Iggy Pop and the paintings of Egon Schiele.
These are works that, though they may "take place" in the real world, are not content to, and so are of a piece with works that don't take place in the real world, not solely for escapist reasons, but out of necessity. This rejection is I think key in formulating a meaningful reaction to the world, in expressing anything of value. And any method that allows us to express such a disavowal of reality is one we should welcome and take advantage of, rather than partitioning off into competing marketing categories.