Read Adam Serwer's post on how politicians handle disaster preparedness. The money quote:
[T]here's evidence that politicians don't get credit for spending money preparing adequately for a potential disaster—just for spending to alleviate disasters' effects.
In short: it's a much better photo-op to be shown in dramatic, sweeping images and video directing the troops -- and fixing things -- than to have carefully invested beforehand in projects that might not be needed until well after a politician's term is finished.
If only we could have a benevolent dictator...