Yes, UX matters, especially when you are a new platform trying to establish your initial user base. But nothing matters in social software as much as network effect; people want to be where their friends are (and/or where people they want to follow or be noticed by are). Like any social network, Scuttlebutt will grow from the edges, as people already using it onboard their friends and family members.

(I had more to say about this but I posted the longer version on Diaspora instead.)