Maybe the old Japan/Korea relations play a role in Nintendo’s neglect?

While I don't doubt that that could also be part of the reason it never released here, it is a fact that the DS sold more hardware than games here in 2007.

In South Korea, many video game consumers exploit illegal copies of video games, including the DS. In 2007, over 500,000 copies of DS games were sold, while the sales of the DS hardware units was 800,000.

https://en.m.wikipedia.org/wiki/Nintendo_DS

And yeah, as far as issues plaguing the world today, software piracy is pretty far down the list of ones that need immediate attention.