I'm not sure that's possible. The only other option that comes to mind is asking people what their interests are and subscribing them to those rather than the s

I'm not sure that's possible. The only other option that comes to mind is asking people what their interests are and subscribing them to those rather than the same set for everyone, but then all you've done is create de-facto, topic-based defaults. You could show people random content, but that's both not PC from a business standpoint and would lead to the outright destruction of smaller communities.