Instead of the USA waiting for the North Koreans to attack them first, I think they should rather try and overthrow that idiotic dictator before he causes any damage to the entire world. He must go by all means.
The risk isn't worth the reward. North Korea doesn't haven anything. It's better to flex muscles and prepare solid defense...the defense proves that this little guy can't really influence any pain toward the US.
And yeah, he must go. There should be a revolt internally. If everyone in that country started walking toward the border, any border, to leave the country for good he might kill them all but at least they'd defeat him. That's a cause worth dieing for.