Actually, on Veritas circa 2004, before we moved to Simple Machines Forum, we had journals.
This was when Veritas still used Vbulletin and was administrated by Silverdawn, who I think was also responsible for the idea.
I don't know if there's some kind of mod for SMF out there that would allow for a separate journal section where the user has control over who sees what. On the Vbulletin site, that's how it worked- you could decide to make your journal public or private. Additionally, journals had their own separate section, they were not a forum, and people could read and reply to your journal posts.
I think this is a wonderful, constructive suggestion and I'm baffled as to why the feature was never reimplemented. Some people used their journals to document their training and metaphysical progress, others used them to post poetry or quotes they liked, and others (like Darkduck) were just completely random and entertaining with what they posted, in a humorous way.
My vote goes towards adding a journal feature similar to the one we used to have, not another subforum.
kobok should get on this