That's debatable.
>It is a tremendous gift, not a punishment- unless you are alluding to some wierd racial monoculture thing.
Immigration is not free. There are social costs which are being dismissed with shallow accusations of bigotry as an alternative to engagement (as you are implicitly doing with your monoculture reference). All peoples are entitled to preserve their cultures, that a particular nation happens to have a predominantly white population does not erase this entitlement.
Cultures clash. Immigrants vote and potentially originate from countries with incompatible cultures, many of whom have no interest in assimilating, yet their votes influence the laws that natives are obligated to follow. If democracy is meant to represent the will of the people, then it is unfair to dilute representation with immigration from nations with totally different value systems. Case in point is the ubiquitous middle eastern treatment of women; how much influence do you want such beliefs to have over your laws and cultural norms? Not even getting to the statistically proven increase in sexual assaults that native women have to suffer on behalf of immigrants in certain European countries. Consider it the paradox of tolerance.