I'll come back to clarity. If the rules of the game--let's call it that--are clear, I think there will be a lot of flexibility within the rules and a lot of innovation. When the rules are unclear, people tend to sit back and argue about “ifs” and “ands”. So clarifying early, and I think regular review as part of the future as well, but I'd say that it's clarity.
On April 20th, 2010. See this statement in context.