Cultures need to learn from each other. They should be allowed to do so from a distance if they so choose and can arrange their private property and contractual associations in such a way as to do so nonviolently. Anything else is illegitimate. Governments fuck this up for everyone.
Discussion
For real. Good fences make good neighbors, and if you tear down the fences and mix everyone up, suddenly you've broken everything.
Like tossing all your organs in a blender and saying you can function even better like that.