Plants evolve to be bitter and spicy in order to discourage animals from eating them, or even poison those animals. What's weird is not that some humans dislike bell pepper. Rather, what's weird is that many of us can eat it at all. Weirder still that many enjoy it.Whats wrong with Bell Pepper? Why does everyone hate it? That shit slaps.
Regardless, obviously not everyone hates bell pepper, but disliking it is associated with picky children, because children are more sensitive to bitterness. This is actually a good evolutionary adaptation that helps children survive the stage of childhood in which they put their mouths on everything.
Personally, I think Japanese parents who try to force bell peppers on their children should be made to eat lots of carrots and lactose until they cry uncle. Sorry, I mean cry oji-san.