A thousand times yes. This will keep the discussion in the older threads alive. I was going to suggest this myself. It would be even better if there was a way to quickly find out where in the thread the discussion is going on at the moment, and which comments are new.
One possible solution is to use flat view, like in the Comments stream, but localized to an article, with the links to a threaded view, linked to from the list of articles. Also, this list of articles should probably show title only, without summary parts of the text.
[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.