It seems most submitted articles are promoted; six of the last ten recent posts are on the front page. That ranges from an article with a score of 8 to one with a score of 38. Furthermore, posting is relatively slow (the tenth most recent submitted is four days old). Because of this low rate, good articles do not slide under the radar. Consequently, voting does not appear necessary to separate the wheat from the chaff. I think the only way to improve the value of voting would be to both increase posting while lowering the bar in terms of quality. To use a simple analogy, there is more incentive to pick the good apples out of a barrel when you know there are worms in it. Currently there are no negative consequences to not voting articles up or down... especially when there are so few that you, Eliezer, are probably reading them all. If there were twenty articles a day, though, we would vote up a good one when we found it.

I'm not suggesting we must submit more articles or lower our expectations - I just think that's the primary reason higher volume sites like Reddit or Digg have higher rates of user voting. Same reason there is more voting within article comments on LW: there are more comments, and your vote may actually encourage people to read or ignore one.