Do you feel like you know members of TFP better when they keep a journal as opposed to just boards/chat?
Sometimes, yes. For example, reading link's journal was incredibly interesting.
Have you thought about starting a TFP journal? Why have you choosen not to yet? (and will you after reading this thread?)
I have not, and shall not. When I do write things in my makeshift journal, it's generally for my own memory assistance. I'm not big on broadcasting things. I may tell people if they decide to converse with me, but I've no reason to post my daily events or feelings on the Internet like that; I have these forums and empty webspace if I want to voice my opinion.
If you do not keep one, what reasons do you have for not having one?
Reasons noted above.