As much as art nerds like surprises in art, I don't think we're really all that friendly to accident. I think we're prisoners of form, when you look at how life really goes. An apparent accident is nice -- say the discovery that Darth Vader is in fact Luke's father, or, less fun, the modernist experiments with language and the "make your own adventure" of 90s hypertexts. The accidents that happen as you're making the art are nice, too, like, say, the sudden understanding that a milquetoast character is really a kind of blind prophet and the pivot of your story. But there has to be some emotional coherence to art, which means "why" attends every choice. Why does this character show up now? What does it mean that he's dressed like that, and who cares? "But it really happened that way" is a lousy defense, even in nonfiction, and I'd bet most editors are pretty quick to dismiss it. Not because editors are dismissive jerks, but because it's pretty rare for big, strong-emotion-generating machines to assemble themselves by accident in short realtimes; as long as it takes to read a novel, for instance.
If you manage to break out of the expected causal relationships (the antique-gun dealer has to leave the pistol on the mantel so the protagonist can ignore it and watch her husband leave with another woman in 60 pages, leaving the gun as a symbol of how the protag deals with the world generally and her reasons for it), you'll still have to make the work coherent somehow. With tone, or unusual connections between elements of your piece,or somehow -- it doesn't matter how. There are grammars to how fiction goes, too, from "Once upon a time" to the expectation that the quaint hypertext you're playing with will not turn out to be a spybot for NSA or a straight-ahead Burroughs cut-up or be written entirely in cuneiform. If you're not working with a well-established grammar, you'll have to come up with some internal structure of your own, or at best you'll have made a marshy curiosity, a one-off.
Combine those restraints with artists' limited imaginations, and I think it's very hard, maybe impossible, to make a fiction that's as strange and accident-ridden as life. It seems to me the mechanical-universe view is actually friendlier to accident. Not because of the idea that things are in fact accidental and chaotic, but because of the acceptance of our limited understanding and data collection. If we can't model a few hydrogen atoms' behavior in a closed space, how can we hope to explain the origins of a particular real cancer, let alone why Uncle Charlie met that floozy at church two months before he died and left her everything? For all purposes, much of life is accidental, then. Until, unless, we have a better explanation, and in the meantime you can believe what you like but there's no scientific basis for it. Unless you're Michael Behe.
Speaking of Behe (and must I? No, but as a Lehigh alum it tickles me to think what he's doing to the administration), here is a quiet but demurring review of his book by Alice Fulton, who's a biochemist here at Iowa and a recently-ordained Episcopal priest.
Would a more mechanical view of life force greater tolerance of apparent accident inside fictional worlds? I'm thinking again of cars and how, in stories, characters attach supernatural meanings to breakdowns. I wonder if a fictional world where characters are simply tolerant of accident would be too boring.