When you really think about it, why do people in the west even feel the need to have an opinion (especially negative) about the DPRK? All the propaganda is so obviously an attempt to manufacture consent to massacre Koreans again as well as to distract from any problems at home.

I think you answered this actually, it makes them feel smart. The underlying emotional cause is a sense of superiority they get to feel towards the evil eastern "regime" (which is just repackaged colonial racism, in the end), which allows them to feel better about their own lot in life. It's the white man's burden.