Keith Nichols,
Your comment wasn't new to me. My response, were we face-to-face, would probably have gotten me arrested for assault. Fortunately, we are separated by distance so that I could not slap you silly. That gave me time to think about the "right" answer and treat it as an honest but misdirected comment.
1. If we take the "don't rebuild" attitude, then we must ALSO ask people to not rebuild in San Francisco, CA and Anchorage, AK (earthquakes). We must ask folks to move away from large portions of Oklahoma - including Oklahoma City and Tulsa, two fairly large cities, plus large parts of Kansas and southern Nebraska (tornadoes). We must ask folks to leave the coastline of southern California (mudslides). We must ask folks to leave Tampa & St. Petersburg & Orlando and Miami, FL (sinkholes) Actually, add Seattle WA and Portland OR to the mix (earthquakes). Now let's get New York, Chicago, Seattle, Buffalo, and Washington to move (killer blizzards). Leave behind the Pacific Northwest (flash forest-fires). Then there's Phoenix AZ, Albuquerque NM, Ft. Worth, Dallas, Houston, and San Antonio TX (killer heat waves).
You can't live anywhere that doesn't have SOME exposure to disaster. So do you cut and run or do you hunker down and rebuild? If you want to go elsewhere, WHERE will you go that DOESN'T have exposure to some sort of natural disaster? (And what do you think will happen to property values when everyone starts moving there? Who would be able to afford it?)
2. N'Awlins is the largest port in the USA by tonnage (though not by ship count or shoreline miles). To rebuild THAT kind of facility adds such a huge cost to the equation that the alternatives that you have to rethink the economics. Add to that the number of railheads, pipelines, and other shipping infrastructure. Then think about what you do to a nation's economy when you abandon their largest port facility.
What do you do in other ports that cannot take up the slack? How long will it take them to upgrade? What do you do with the pipelines, railheads, and such because you can't make the connection without rebuilding those facilities elsewhere - and what do you do in the interim? What do you do to the nation's economy by deciding to close the city and move elsewhere? You are quick to say "Don't spend the money" but you didn't stop to think that people have to live somewhere - so you will just spend the money anyway.
3. A large part of the problem was human negligence, not the disaster itself. The levees would have reduced the flooding had there not been massive failures of responsibility among the quality control engineers in the months after the levees were built or upgraded pre-Katrina.
The two worst breaches were caused by some basic hydraulics. a) Storm surge raised level of water in canals. b) According to Bernoulli's Principle, that means increased flow rate towards the drain point. c) According to sound principles of hydraulics engineering, that increased flow rate increases the pressure on the sides of the canal. Which increases the friction / drag values. (Solids call it friction; fluids call it drag.) d) The failures occurred at points where the increased friction undercut the levees because the clay used to build the foundation was deficient. In other words, sub-standard choice of materials that could have been - but was not - stopped by the inspectors. The above discussion isn't a guess or conjecture on my part. The U.S. Army Corps of Engineers published those findings in a report not too long ago, taking much of the blame on itself. And rightly so.
A separate "human failure" issue was that in a couple of areas, the pumps were allowed to stop working. (That's what got my house.) The local government did not ask for someone to stay with the pumps. Current studies indicate that if the pumps had been kept active, they would have reduced the flooding by such a large amount that my damage might have been limited to carpets and floors. But that isn't what happened.
Now the parishes are building "safe" houses for the pump engineers so they can stay during the storm and restart the pumps when needed.
4. As far as flooding goes, we had an article in the local news rag regarding why Sieur d'Iberville and Sieur d'Bienville (actually, Jacques and Pierre LeMoyne) founded the city where they did. They picked the first place up from the mouth of the river that WASN'T flooded out. It was the first place they could have built (and did build) a fort to control the river north of that point. Farther north, they might have built a better, more stable, and less floodable city, BUT it wouldn't have provided full control of the river.
5. To a certain degree, Keith, there ARE some areas where there is talk of a reversion to nature. Some parts that got 15-20 feet (yes FEET - over the tops of one-story houses and about waist-high in two-story houses) of water might indeed be too expensive to protect. But most of the city was NOT that way.
The problem with THIS approach is a variant on Eminent Domain. We are not allowed to take property from someone without paying for it. We (in this case, governmental "we") are not allowed to make decisions that negatively affect property values without just compensation. Abandonment of the repairs would certainly have that effect.
But the folks who are mostly affected by this were poor and didn't own their property anyway. They were renters or in subsidized housing. So who owns the land? The lawsuits and charges of racism have been abounding.
I feel I can safely assure you, the water was race-neutral. It was, however, NOT neutral with respect to physical elevation. The rebuilding efforts are still heading towards the worst areas, but as noted earlier, there is a massive infrastructure problem that slows down progress there. And that just happens to also be an area that was not racially balanced. Hence the loud squawking of the populace.