For now, a submitted story stays for hours, maybe days in the voting queue, which is good. Comments are made and they may improve the quality of the story. Being able to incorporate them would definitely improve the quality of stories published.
Some more ideas on that: This is how "peer review" works in the sciences: You submit a paper, three reviewers read the paper, make comments and give a recommendation, if it should be published. After you get your paper back, you normaly try to incorporatre some of the suggestions, but you don't have to.
Back to kuro5hin: Besides making changes myself I might want to allow specific story editors to make fixes. Just "rusty". Or "all admins". Or "all users".
If we allow to make changes to be made on a story, after already some voting took place, there is a small chance of abuse: I might wait until I just just enough votes that I only need one more. I change the story into a bogus story "M$ ate my ballz", and vote on it with my second bogus account, pushing it over the threshold. But I guess this is just a theoretic possibility.
BTW: I know quite a bit of Perl, and could implement such editing myself. I just need a OK from you and rusty and I would do it.