Was this the only one that was closed? I doubt it.
I guess the point about this bridge being closed is it was the one close to the downtown area, superdome, etc to which people could have walked across and gotten to other areas. This bridge is some 1 1/2 miles from from the Superdome at most. I-10 was impassable both east and west after the storm for sometime due to water or roadway destruction. It will be months before some of it is rebuilt.
I think the long of it is that after this thing is over and some order of life is restored a complete analysis of the event will be done. Who did what, when was it done, what communication was available, what transportation was used or not used and why, who should be in charge, etc, etc will be done and a better plan will be developed. Until then we need to get on with the clean up and restoration process such as it will be done.