Re "Why doesn't someone make a movie about the Levellers?" Your wish is granted. Winstanley is a British film made in 1975.
Real-life activist Sid Rawle played a Ranter (English Revolution period anarchist-type group). Uber-hippie Sid Rawle helped me set up a squat in Kentish Town in the mid seventies! You can see the movie for free here. (Re English accents: Gwyneth Paltrow and Reese Witherspoon are both flawless.) https://www.youtube.com/watch?v=qW12-yt2o6A https://www.youtube.com/watch?v=qW12-yt2o6A
