I went Friends Only because I don't feel comfortable knowing that anyone could be reading my journal, and I wouldn't know it. If someone wants to read it, they can tell me, I can consider them, and maybe add them as a friend. There's no reason for someone to read it in secret. That's especially true now that one doesn't need a code to make a livejournal.
Also, I don't feel comfortable with real life friends reading it. I don't know why, and I don't know how it's much different, but it is.
There's your explanation, heh.