I agree about the social tie aspect. YouTube, Facebook, Twitter, etc. are all big because they foster community directly or indirectly as friends or followers.
If Steemit plans to retain users there needs to be a social incentive on top of the monetary incentive!
Users need to be able to associate visibly/transparently with each other, and to show others who they vote for and what kind of content they vote for. Maybe like individual public Upvote statistics represented in infographics.