I think people hate because it requires no brain power, and is therefor easier than accepting that people can be different and have different opinions, and still be okay.
Different is threatening and has to be explored or it remans a threat. You see this behavior in dogs who bristle and growl until they've sniffed around a bit and found out things are alright. But, for the intellectually lazy or timid, it's too much effort to get out of the mental box and explore, and find out that different thing is okay, maybe even better than what they are used to.