The feynman lectures were aimed at the smartest students at caltech to keep them interested in physics. You have to consider who the audience was. If Feynman made a series of lectures for physics 101 where the majority of students had no physics experience (or a physics 101 for the general public), then he would make the material different. You can't look at one set of materials by Feynman for one group of students and conclude that he isn't a gifted teacher. There is a reason he is called the "Great Explainer." There is a reason people called him the Greatest Science Teacher while he was alive.