I put a lot of consideration into this. I wanted to keep it smaller, since it's always easier to add than remove permissions. Unlike KV, yokozuna isn't mature enough yet to know how people are going to want to use it. Practically speaking, I'm sure there will be users who can search, and administrators who can manage indexes and schemas. I'm open to adding more, but for 2.0 I just didn't see the value in it.