Seems like micro-currencies are created to make the local economy more resilient and to reinforce the regional identity. Bitcoin, being a volatile and global currency uncontrolled by anyone, wouldn't suit these needs. A small local community would be at the mercy of global speculators who often decide to dump Bitcoin when they feel like it can't grow fast at the moment, and they would be powerless to stop it. But in case of their local currency, they can control it and maintain its value.