Worthwhile communities need to be maintained by barriers. The kind of barrier that I personally enjoy most is, "Crappy enough interface that only people who really like the content will be motivated to show up."
I think it just correlates with the presence if images. Also StackExchanges have excellent UIs, APIs and still very good content. StackOverflow itself could also be worse.
That is a good comparison. StackOverflow has a good API, but maintains itself with carefully thought through and zealously enforced moderation rules.
I grant the existence of useful content there and a good API. However after one too many brushes with how differently moderators think about stuff than the people who I liked talking to did, I have demonstrated the truth of my comment by choosing to leave.
StackOverflow works for a lot of people. But for me, personally, a stripped down interface and less moderation is a better experience.
