I don't get the argument here... Countries should just be nuking each other all the time because it's not that bad? The US should have just dropped some nukes on Iraq and it would have been better?

Nukes kill children. Nukes destroy hospitals. Nukes give whole body third degree burns to everyone who isn't immediately obliterated. Nukes irradiate the land and sky so much that we can date paintings based on the presence of isotopes spread by nukes in the ink. Nuclear warfare is a war against humanity.