If Katrina had been the first big disaster that FEMA had ever dealt with, I would give your argument some credence. However, it wasn't. FEMA had performed admirably and quickly in numerous disasters prior to Bush putting Brownie in charge who, upon orders, restructured FEMA in ways that compartmentalized operations which, in turn, slowed inter-departmental communications and response times.
Brush broke it and then fixed what he broke. I'm not impressed.
Add to that, the populace is certainly more likely to take evacuation announcements seriously after Katrina. From everything I've heard, that went a long way toward a successful evacuation as well.
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"If a 'right' exists for me, but not for thee, then it's not a right but a privilege.' - Fred Clark