I think Bret Victor underplays the importance of liveness ("almost worthless", eh?), and doesn't touch on the possibilities of making programming a shared experience, that is itself culturally meaningful, inclusive activity, e.g. musical. This is what Sam Aaron and other live coders have been working on for the past decade. It's a totally different approach really, through making music together, nonstop for years.. Sonic Pi is impressive and successful because it's grounded in actual arts practice, not extrapolations from rigged demos.