Yeah, it's actually not that funny despite the failure. This is like saying "ha-ha" to the Taliban for failing a suicide bomb attempt.
Part of the world's problem are caused by angry people that will use any opportunity to use their resources on achieving whatever crazy goals they have (like striking out at their wealthier neighbours out of jealousy or sheer joy of destroying things). Even with inferior technologies, extremists from the middle east have shown us that it actually isn't that difficult to cause a high degree of casulties and collateral damage in developed countries.
But in North Korea's case, it does have a very large standing army and sufficient capability in bombing the **** out of its neighbours.
And yes, if M.A.D really happens, it wouldn't be like FO3. There wouldn't be permanently-preserved sugar pies packed in bombed-out Walmarts waiting for people to pick out and there aren't rad-aways to instantly cure people of all radiation exposure. On the upside, there shouldn't be any ghouls, rad-scorpions, and super-mutants roaming around 200 years after the holocaust.
You should look up the definition of MAD.
MAD is only relevant when you have two states which can wipe eachother out, not when you have one physically massive state that can wipe out another physically minute state that is woefully inept and has only a handfully of barely kiloton quality nukes at most.