Koreans are descended from Han Chinese and Japan are closely related and Iran is just close. In any sizable group, there will be people who have genetic markers that are similar to other groups.
It’s possible that the reason why it’s infecting the rest of the world at a slower rate is because the most virulent aspects of this viruses have been contained by the trading of genetic information.
I don’t see it as a problem for myself to be worried about.
Or it could be that the rest of the world has had more lead time than the Chinese and containment efforts have slowed down the spread. However, to your distance argument - Italy is closer to the USA than to China, but everywhere is pretty close to everywhere these days.
Containment is key. It gives us time to develop countermeasures and takes some of the load off of our medical infrastructure. But each time containment fails it puts stress on the rest of the containment efforts.
We’ll see what happens in Italy and S. Korea, where we at least have a chance of getting reliable information. Right now, Italy has more deaths (7) than recovered (1), with 275 unresolved cases. S. Korea is better, with 10 deaths and 22 recovered and 945 unresolved cases. But even if there are no more cases and everyone currently infected recovers, those are still significant mortality rates.