I miss it too. I think the reason it was so good is that only smart people knew how, or cared enough, to access it. Just by the nature of it being new and strange and difficult to use.

I'm not sure how such a thing could be re-created, other than through artificial barriers, but there are already enough places on the net that are annoying and difficult to access, yet aren't filled with these same smart people.

Yet there are forums like hackernews that are very high quality and retain some of that early-internet feel.