For a long time, I was skeptical that model-free RL would ever be useful on robots. Dramatic advances in simulation have changed my mind. With domain randomization enabling sim2real transfer, it may soon be that classical control is rendered obsolete.

Why use a learned policy instead of a classical controller, you ask? The classical controller is only as good as the dynamics model. The learned policy, when trained with domain randomization, is robust to error in the dynamics model and external disturbances.