The author still has to know what's inside the gaps. Also, the gaps have to look coherent - they can't appear to the reader as noise, or it simply won't create the right impression, no matter what.
You may be overanalyzing here. I've never published anything that I would've considered sending in to a science fiction magazine - maybe I'm holding myself to too-high standards, but still, it's not like I'm outlining the plot and building character sheets. My goal in writing online fiction is to write it quickly so it doesn't suck up too much time (and I quite failed at this w/r/t Three Worlds Collide, but I never had the spare days to work only on the novella, which apparently comes with a really large productivity penalty).
I think Alicorn is certainly not overanalizing in the sense that fiction is always fiction and usual methods of analysis apply regardless of the author's proclaimed intentions or the amount of resources spent at writing. On the other hand I think Eliezer's fictions are perfectly good enough for their purpose, and while the flaws pointed out by Alicorn are certainly there I think it's unreasonable to expect Eliezer to be like a professional fiction writer.
As promised, here is the "Q" part of the Less Wrong Video Q&A with Eliezer Yudkowsky.
The Rules
1) One question per comment (to allow voting to carry more information about people's preferences).
2) Try to be as clear and concise as possible. If your question can't be condensed to a few paragraphs, you should probably ask in a separate post. Make sure you have an actual question somewhere in there (you can bold it to make it easier to scan).
3) Eliezer hasn't been subpoenaed. He will simply ignore the questions he doesn't want to answer, even if they somehow received 3^^^3 votes.
4) If you reference certain things that are online in your question, provide a link.
5) This thread will be open to questions and votes for at least 7 days. After that, it is up to Eliezer to decide when the best time to film his answers will be. [Update: Today, November 18, marks the 7th day since this thread was posted. If you haven't already done so, now would be a good time to review the questions and vote for your favorites.]
Suggestions
Don't limit yourself to things that have been mentioned on OB/LW. I expect that this will be the majority of questions, but you shouldn't feel limited to these topics. I've always found that a wide variety of topics makes a Q&A more interesting. If you're uncertain, ask anyway and let the voting sort out the wheat from the chaff.
It's okay to attempt humor (but good luck, it's a tough crowd).
If a discussion breaks out about a question (f.ex. to ask for clarifications) and the original poster decides to modify the question, the top level comment should be updated with the modified question (make it easy to find your question, don't have the latest version buried in a long thread).
Update: Eliezer's video answers to 30 questions from this thread can be found here.