Personally, I think letting the boards sink or swim on their own merits is really preferable, and will ultimately result in better quality boards and posts.
Yahoo and RB stand out as two shining examples illustrating the opposite. Human nature being what it is.
For our long term survival and prosperity, we have to differentiate ourselves from our competitors and the way we've chosen to do so is quality. In signal/noise ratio, level of discourse, freedom from spam, vulgarity and personal attacks, and, coming very soon, superior non-messaging tools to turn us from "message boards" into "Supersites, featuring great message boards". That's the niche in which we want to make a living and believe we can do quite well.