Back on the topic, I don't think it would be a good idea. Aside from the vague explaination for how it would attract recurring visitors, social networks also have a way of isolating the population into peer groups, another way of rephrasing it, High School. I don't want CYOA to end up with one section goths, one nerds, and one one jocks. Why this would be a problem? Story ratings. If you have enough friends, everyone will be voting for you not because your story is good or has quality, but only because you're popular, which in this case will probably be JJJ. ;p
Secondly, this is a story game site, not a social networking webpage. If intermingling story games and social networking was so instrumental to success, the most popular thing on facebook would be your friends and story games. However, it isn't because they don't mix. It is like cross breeding a male horse and a mouse, and not in the test tube way.
Third, it may begin with a friend list, but before you know it, there will be a forum ignore list or however it would be implemented. There will be group trash talks, and petitions to take someone's story off the site just because your group doesn't like him/her.
Fourth, I would like to think this is a midly professional site made for people who have hobbies or writing careers, not high school. Ganging up and forming a country only invites prejudice, not harmony.