Does it make any sense for people to be hostile toward one another because of their choices of stereo gear?
No. There are so many other things for people to get hostile towards one another about, like the color of their skin, their religious or political beliefs, or the way they part their hair. Human beings seem to have a long history of hatred based upon their differences. The stereo example is simply a microcosm of what's been going on throughout history which is certainly not going to be cut off through homoginization. I think something like what you are suggesting could only come about with some kind of sweeping altered percetption of the world. One that does not see things in terms of black and white, right and wrong. I also think that as long as we're talking about human beings, that this is utterly impossible. It is our nature to attach meaning to virtually everything. The best we can do is become aware of what we are doing... step away from ourselves in a way and get some perspective that is less egocentric and more objective... that, or we can just keep on hating and killing each other off.
Marco