It isn't obvious to me that additional clueless comments are superlinearly harmful, that their harm outweighs the benefits of greater publicity, or that the problems with defection that you mention are serious enough to prevent a collective solution from working.
Can you think of other online communities that suffer or at least go through great and unpredictable change due to a high influx of new people?
Recently reporters from two major national magazines contacted me in preparation for doing stories on Bitcoin. This reminded me that Wired magazine did a cover story on the Cypherpunks in its second issue. I think the LessWrong community is already larger and more active than Cypherpunks were back then, and potentially more influential, but there hasn't been much publicity on us. I'm tempted to suggest doing a story on LessWrong to one of the reporters. Is this a good idea, or bad?
More generally, do we want more publicity, and if so what's the best way to go about getting it?
ETA: Would it be bad etiquette to reveal the names of these magazines at this point, or even to say as much as I've said?