DPRK seems to know a LOT more than HTML. They are not dependent on (read vulnerable to) the Internet in the burgeoning ways of the rest of the world. They clearly see it asymmetrically, as our Kryptonite:
This doesn't tell me they know what they're doing. This tells me they are scrambling for a few million here and there when they can. Wouldn't you guess that a state funded actor could be much more dangerous than encrypting your personal files and demanding $400 while leaving a kill switch easily available?
Here's where the common usage of first and last name break down: his family name is Kim. I suspect it's along the lines of what you're getting at: to keep the name together.
I'm not sure how interesting this is in and of itself. It might be interesting to see if this is a special case. If it is, is there a particular reason for it? One could speculate all kinds of reasons, but I'm not sure how useful that is without actually knowing why.