I think it's absolutely naive to assume that if the DNA goes, the institutions will remain intact. For example, if America, a system bourne of the intellectual culture of British Aristocrats, were to become 60% 80-IQ African/Latino, our democracy would gradually cease to function. Many of these people simply aren't smart enough to fully maintain our institutions. I'm not saying "ban all others, forever". America is different. But look at how free speech laws are already starting to go, and it's always relating to race when they do!. We need to keep the genetic composition of the USA front and center when it comes to immigration policy. To let in millions of extremely low IQ and/or aggressive ethnicities, as Europe has done, would be a terrifying mistake.
Here's the political incentives since the 1960's: Minority immigrants vote for the left. The left rallies around race issues and pushes more immigration, and wins more seats. Rinse/repeat. Immigration issues are the bread and butter of left wing movements around the entire world, largely for this reason. They get the votes, damn near 100% of them. It really is that simple.
Japan has a right to keep the cultural/ethnic composition of it's people intact. That means that if you show up in Japan, with a boatload of East Russian economic migrants, they would laugh and turn them away. The same goes for Israel. Some migrants once showed up in Israel. They put them in a fenced camp and literally flew them back to Africa. (dusts hands). Europe on the other hand, is told they must literally stop being ethnically european. They need to accept millions of millions of africans and arabs into their societies, mate with them, and start a "new Europe". To not see this double standard is absolutely heinous. It took me a while to see it too, but when I saw it, I got angry. Why are the European nations forced into this? These weren't public referendums... they were top down orders imposed by political elites, for the reasons I described above (and others).
If you seriously are asking this question, look no further than a prison. If you don't separate people, by race, they are more violent than if you just left them to their own kind (in which case, as you point out, they would still be violent, just much less so). There's a ton of other data about too, but please look for it yourself. Also, just look at any "diverse" city. It's (almost) entirely self-segregated by neighborhood. People stick to their own, and feel uncomfortable around others... and we just have to "take that hit". That's okay, and we don't have to "hate" the other races, but we do need our own homes and our own "extended families" just for mental health reasons beyond our control.
Race is a phenotype. But don't just change the word and then act like it accomplished something. Race is real. And race is a reliable indicator of a tight cluster of traits that we can predict accurately. And we should take that factor into account when considering our immigration policies, especially in europe.
Where the first yurts were built is not what I'm talking about. I'm talking about the readily identifiable ethnic groups, all of them white and asian, that built what we call "global civilization". I'm saying Sub-Sarahan Africans just never built anything in their existence as a species. They are simply not as good at civilization, and now we are living in the age of civilization.
Ultimately, I'm on your side. No one is out of the race, there are Black Einsteins, and everyone gets the job interview. I get it.
But "the human species" is simply too unsophisticated a conception. It's like saying the "dog" species. There are many different types of dogs, some good at different things than others, just like humans. We have evolved in seperate niches for over 100k years, and white Europeans are simply a different ethnic group.
So again, I think we need to pursue nationalism based on culture/ethnicity because it's necessary to keep order. I don't think it's desirable, or possible, to just "blend" all of the african world into the european countries for no reason but blind altruism. I think it's irresponsible, we have a right to leave our culture the same as our fathers left it for us, and that includes the fact that our culture was a European one. Genes matter enough to necessitate the creation of ethnic states. This proposition will be more peaceful than forcing a sort of vulgar, rootless postmodern globalism, which is what is currently happening w/ projects like the EU... and as I've explained, these projects will ultimately fail.