Well - I have to disagree completely. However, it varies according to the TYPE of site, and where within the site.
Note, I don't disagree that a thread is a conversation. That was the core of my anti-intelliTXT campaign on Daniweb (which was succesful there, where I'm a moderator. On Tek-Tips, the response was just to ban me immediately.

)
However, on a site like this, which is about vbulletin coding, the coding discussions should be very on-target, and extremely well-moderated. That is because the "conversations" are not only between the thread participants, but for search engines, future members, and by extension advertisers and so on.
Thus, I think they need to be heavy on content, light on fluff.
I used the analogy in regard to vbulletin.org that you could sure get the "vitamins" you need from a thread, but you had to eat 50lbs of marshmellow to get them, by which time you're ready to puke. I'd hate for that to happen here.
On my own site I moderate ruthlessly, and it's very much appreciated by the membership. I'm not after a riotous jungle of a forum... I want a bonsai.