This is not "starting to become" for South Korea. The fact of the matter is that South Korea is far more democratic now than it was during the Cold War. These laws restricting the dissemination of North Korean propaganda have been in place for decades, and were often used with the tacit approval of the US in years past to suppress dissent.(In fact, until about ten years ago, it was technically illegal to import Japanese pop music into South Korea!)
The only difference now is that their use is becoming increasingly controversial. This, at least, is a good thing.