I wouldn't call it hate. Like the U.S. Armed forces, it's more of a love or preference for each group's own methods. For example, I Warlock would not throw a knife when he can shoot a beam from his hand. It's just preference. When your friends die daily, you've got to find ways to lighten your mood among the ranks. I guarantee that if all three were fighting together and one died, the loss would be sincere, regardless of class.