Completely agree. I know the regime in North Korea is crazy, but I really don't see them caring about this at all. On the other hand, they're often the butt of jokes in the west. Just look at all the "you've been banned from r/pyongyang jokes on reddit. Or 'The Interview' itself, which based on the trailer, seems to be laughing at the same stereotypes. I think a bunch of hackers that frequent 4chan have a lot more motive to continue this whole joke than North Korea itself.
I'll hammer on a third agreement. I posted a similar comment elsewhere in this thread. This really does make the most sense. I cannot imagine that North Korea has the motivation, brain power, and coordination to pull off something and actually rattle our culture, let alone be adept enough to know that Sony is a good target to attack Hollywood.
Companies are "brands" for hackers. "I hacked Target. Home Depot was me." etc. Sony is a huge brand. Keep the lulz going, and see how big it can get.