because he's a chicken$h!t coward who wouldn't have stood up to a man. That's why he beat smaller people/women.
I honestly believe his "stunt double," the driver of the getaway vehicle (AC), killed them because she/they were making OJ upset and that was making it hard for him to "concentrate" during interviews, ads he was cutting, or in his bit parts in shows or movies. His being upset was messing with the gravy train, AC's main/only source of income as part of his entourage. SUPPOSEDLY, OJ insisted, when he accepted his scholarship to USC that his best friend, AC, also get one.