No, the North Korea point is not a good one, it is naive and simplistic. If North Korea wants to blackmail us with its nukes and given a worst-case scenario actually uses one in South Korea, what happens?
A lot of innocent S Koreans die, yes...but thinking from a STRATEGIC standpoint, the US doesn't lose any major resources or trading partners.
What happens if Iraq gets a nuke and decides to use it?
Assuming they use it themselves, they have the ability to make inaccessible some of the richest supplies of oil in the world. And if they are able to successfully use their nukes to blackmail Saudi Arabia and the rest of the oil producing nations of the Middle East, they could basically achieve control over the pricing and distribution of oil around the world.
Now a bunch of the isolationists are going to scream, "See! It's about the oil!"
No, it's about the stability. If Iraq controls the oil, do you think that's the end of it? That the situation will remain like that for long?
No, what's GOING to happen is that SOMEONE is going to attack Iraq because they don't want them to have that sort of control. If we don't do it now, Israel will do it later and they will certainly respond with nukes if Iraq goes to WMDs against them.
Then you have World War III, ladies and gentlemen and I am not exaggerating.
The Iraq situation is a ticking time bomb and if we don't deal with it now while we can, it will indeed blow up in our faces.