[Edit: Issues, Bugs, and Requested Features should be tracked at Google Code, not here -- matt, 2010-04-23]
Less Wrong is still under construction. Please post any bugs or issues with Less Wrong to this thread. Try to keep each comment thread a clean discussion of each bug or issue.
Requested features... sure, go ahead, but bear in mind we may not be able to implement for a while.
Because quality and truth are separate judgments in practice, and forcing them to be conflated into a single scale is losing information. To the extent that truth is positively correlated with quality this will fall out automatically: highly truthy posts will tend to have high quality. Low quality and high truth are not opposites.
I agree it's losing information, but that's something you have to weigh against the inconvenience of multiple dimensions. To the extent that truth is positively correlated with quality you're just making people click twice, and I suspect clicks are a limited resource.
As I see it the voting system is there to put comments in a convenient order and remove the really bad ones from sight, not to provide opinion poll information.