Out of the shallow villains from DBZ, Broly seems the most so. While Cell was programmed to kill Goku and took joy in facing a strong opponent, or Frieza reveled in conquest and victory, Broly lacked even that much complexity. Broly wanted to kill Goku. Unlike the Androids, he was not programmed to do so by someone with a grudge, unlike Vegeta, it wasn't out of some drive to be stronger. We are meant to believe that as a young child, Broly heard Goku's cries, which etched so deeply in his psyche a hatred for him, that even as an adult, the hatred has only gotten more virulent.
At a cursory glance, this seems one of the weakest reasons for a villain to try and kill Goku. Broly has no other plans, no ambitions. Does he just enjoy destruction for its own sake? However, unlike most of the antagonists Dragon Ball holds, we see Broly's past. We see his family, his origin, and looking deeply, we see something far more tragic than at first glance.