So, when you get really popular and someone wants to make a Collected Work of You, you can just take that nice little anthology made out of dead trees, pop it in the Republishizer, and off you go, right?
Hmmm, well, actually, you'll probably take the last copy of the story that you had on your computer or in typed manuscript form, typos and incorrect name of the main character's cousin and all, and give them that, and then they'll go through the exercise of editing it (again), including sending it to you and having you make and approve corrections (again - hopefully remembering to re-make changes like that name), which you'll send back to them (probably without keeping a copy), then they'll put it on another set of slices of mashed dead tree, and send you a few, bound and ready to read.
And you still won't have a clean, reprintable (by which I mean electronic fulltext, preferably at least .rtf) copy of your work.
Odds are, if you are an author, unless you've sold work into an electronic market you can copy yourself (and have done so), you don't have a workable electronic copy of the end product of any of your work. This is partly because the process of editing is not viewed as the collaborative art form that it is. You sell the story, or the rights to publish a book, to a publisher, and they clean it up (you help) and publish it. You own the copyright, if all is well. It says so right there on the inside cover. You just don't get a copy back of the final version, except in print.
So if and when the publishing rights revert to you, say, after the magazine is on the rack, or the book goes out of print, and you want to reprint your story or book, or you want to put it up online, maybe to get some more money from it or at least let your loyal readers read it, what do you have? A diamond in the rough. A mid-process manuscript.
[If your publisher is still in business, your reprint publisher can possibly negotiate with them for a copy of it, sure. If they still know where it is, which they probably do. Or they can OCR a print copy of it. And then proof that, because the process is not perfect.]
Your publishers are not maliciously cheating you - this process is simply a holdover from when the printed copy *was* the final copy, when print was done from a bunch of little pieces of type that were not saved in that particular configuration after the print run was, well, run. And some authors still don't ahem, own computers, and so would not necessarily appreciate having an electronic copy of their own text. But they are becoming the minority. You, the majority, should have a computer-readable copy of your work.
I'm not entirely sure, but I suspect that all you have to do is ask. It's worth trying, at least. (Let me know how it goes). Failing that, you might at least stipulate it in future contracts, so you get a copy of your future work. I mean, everybody has enough to do without editing the same thing over and over again, eh? I thought so.