That's a very good point. It's easy to lose sight of how much the piggies liked each other and cared even though they seemed to selfishly keep singing happily when they fell off one by one. Or happily for part of the time as in the case of the leader after the second piggy fell. But you do have to admit that when the leader tells his remaining buddy to watch his step at that particular moment it was very obvious indeed that he cared about him, wasn't it? He must have been very sad that both his friends were dead even though naturally he had to cover it up for the sake of the audience's enjoyment right?