Last night The Simpsons aired its 636th episode. That might seem like a completely arbitrary milestone, but it marks the point where the show beat Gunsmoke’s record as the longest-running primetime scripted series. It’s an impressive feat, to be sure. Unfortunately, it’s one that also highlights The Simpsons’ refusal to grow or evolve over the course of 30 years. After 636 episodes, why can’t The Simpsons take more risks?