Well . . . New Orleans was kind of a perfect storm situation (excuse the pun). Even a Category 5 hurricane would not do that kind of damage in most cities, as most cities don't sit below sea level, next to a big-ass lake with shoddy levies.
However, ice storms, hurricanes, earthquakes, heat waves, Godzilla, etc., can make things pretty freaking bad. From what I'm told, here in Miami, when there is a hurricane coming the grocery stores are literally empty. People make a mad rush on food, gas and home depot. If you aren't prepared you can be pretty ---fouled up beyond all recognition---. When the storm is over it's gonna heat up, and maybe that won't kill you, but it's gonna make things pretty tough if you don't have access to any food. And what if the municipal water supply is compromised?
With that said, I have a 72 hour kit. It's sealed in a coffee can. I should have water to go with it, but don't.