This day and age, we can't afford this.
Throughout history, there have been periods of of cultural xenophobia. This has almost always led to stagnation or being conquered.
Nazi Germany is a prime example example of the latter, as is early 19th century Japan.
In Germany's case, virtually everything non Aryan was seen as inferior. So much so that campaigns of extermination were begun. The war they started to "prove that truth" backfired horribly and resulted in the complete conquest of Germany by foreign powers. Powers that proved that mixed race societies have the moral high ground and will to prove it.
Japan in 19th century- before Matthew Perry sent the mission to open the country- the island nation had more or less sealed itself from the world, trading only to select traders in restricted ports. This came at cost. By 1854, when Matthew Perry's flotilla sailed into Edo Bay (Tokyo Bay now), belching smoke and stacked with cannon- of a type never before seen- the Japanese were forced to consider an awful truth.. The world had left them behind. They were no longer in a position to even defend themselves as their technology simply was obsolete. The rush to modernize Japan began, and by 1905, their fleet and technology was comparable to any European power. 50 years to catch up, but somehow, they did it.
On the flipside, countries that have opened their borders to trade, either through conquering or aggressive trading have enjoyed enormous success.
Holland in the 17th century was the richest country in Europe. They had an unrestricted trade policy that saw their influence spread across the globe, India, America, Indonesia, Africa, South America, even Australia was once called New Holland. This tiny nation went on to fight three separate wars with Britain, including raiding London, before the population difference finally showed itself.
For about 200 years, Britain, largely through trade with her colonies, became the ascendent nation.
Trade brings wealth. The USA grew that way, despite two world wars, into a very successful economy- but it has taken China 60 years to modernize, and now they, with an economy based on trade, are number one.
With instant communication, free flow of information, and access to it essential for a nation to remain sovereign in today's world, there is no place for Xenophobia. Globalization on this basis is inevitable, and likely necessary in the evolution of human politics. Especially if we are to expand our horizon and look to the stars.
I just hope they don't stamp out individual rights in the process. There is a very real danger of this happening.