Oh, most certainly they did. It's just that, if reports are accurate, the Superdome is designed to withstand winds of 150mph -- which is just about what Katrina is packing as a Cat 5 storm. The Dome will be 'worked' to it's ultimate design limit -- which is never a comforting thought for any engineer.
Putting several tens of thousands of citizens inside the Superdome was probably the best of a list of bad options. Still, this will avail the governor little if that Dome collapses. She should avoid making statements that could boomerang on her.
Sometimes your only choices are between the "bad" choice and the "even worse" choice. The Superdome was the "bad" choice.