for millions of people, you should always err on the side of caution and consider every contingency. Period.
One thing that the governor *should* have known is how quickly any sort of precipitation would turn to ice in those temperatures. "Should" is a mild word in those circumstances. It is his responsibility to know.
He and the mayor were derelict in their duties. Nobody, whether in business, the police force, in the education community, in medicine, and certainly in the military, would be able to get away with this monumental failure and negligence. An ordinary citizen would be fired and/or charged with a criminal offense if pain, suffering, and injury were their faults.
Also, I have to add that El Paso, where I live, has snow as rarely as Atlanta. And when the possibility of a snow event arises, the trucks are out at least ten hours before and continue salting even well past the event. Overpasses, bridges, access roads, mountain passes, and other secondary highways are closed. Of course, schools are closed. Emergency Command centers are set up by local government and hospitals. People are well-informed about what to expect, urged to prepare, and encouraged to stay off the roads.
And if roads are treacherous, drivers are told to stay home, except for emergencies.
Look past the mayor and governor's rhetoric. Look only at their actions. Then, you can easily see that they did nothing. And as public servants, responsible for the well-being of a huge city, they were negligent -- perhaps criminally.