I have noticed that most posters consider any defence of ethnic homogenity to be racist. Given that most of you are from highly multiethnic USA with a troubled racial history that's not surprising.
But given that many Asian and European societies are historically monoethnic or almost monoethnic I personally don't think that's true. You can be against immigration of people from other ethnic groups without necessarily having any feeling of racial superiority or prejudices of people from a different background.
Fx. South Korea is about 99,98% Korean and all Koreans I have met define their national identity as ethnically based and prefer their country to stay that way. Does that make them racist?
Personal I don't think it's worth anyones time to bring the issue up, as you can see in this thread the result is hysterics, insults and namecalling, rather than anybody discussing the issue.
I think one of the reasons is the class make up of this board, most people here is young and upper middleclass suburbanites. For such a group there's little effect in living in a diverse neighbourhood. Where such things matters are for less well-off groups like in a working class or mixed working-lower middleclass neighbourhoods, where people are single out because they're the Other. If you rich diversity are a net positive something which set you apart from the pack, it also do so among the poor, there it just make you a prey for unpleasantness.
That's the effect on a individual level. if we look at societies, a diverse society is a less solidaric society, people help people who are like themselves. We see it in USA with the generic welfare queen (Black of course in people's imagination), of course we also see it in Europe with the growth of xenophobic parties and the general strengthening of the anti-solidaric parties. People are not as willing to pay taxes, if they feel the money goes to the Other. Americans loved the growing welfare state, until Blacks was allowed to partake in it, in the same way in Europe the love of the welfare state has cooled as people feel it more and more goes to immigrant groups.