cos

It's less about how interesting you are, and more about what you use your LJ for. If someone friends-locks all their posts, for example, then there's no point in putting them in the group. If most of their public posts are life updates, then I think that'd most be interesting to people who know them, so I don't add them to this group. If you used your LJ primarily for posting your comics and your reflections associated with them, I'd probably add you to it, but that's not to say that I think you should do that. (Actually you probably knew most of this, but I'm writing it for future visitors to this post :)

Then again, there are rare exceptions like petra_quince, who posts rarely and generally does write about her life or things that she saw or experienced... but writes so well it almost doesn't matter what she's writing about. Which is why I made this post to specifically recommend her journal.