If you've ever been on Bourbon street, it is a very interesting place. During the daylight hours, the street is filled with tourists. As the sun goes down, the crowd evolves into partiers. By 3am, most of the people are going to be pretty wasted. I would say this would have been a lot worse if it happened a few hours earlier. There would have been a lot more people on the street.
The Sugar Bowl is moved to today (Jan. 2). It won't be as much fun because of this.
Officials can't really say for sure that everything will be secure. Of course, they never can really be sure of that. I imagine there will be lots of lawsuits against New Orleans for allowing the truck to get through the baracades.