Seeing as you used the term "excuses", I don't think you are interested in honest debate here.
Which is another reason why taxpayers are getting less and less interested in sending y'all tens of billions of more money - because of the attitudes of folks like you.
But, since you are asking, albeit in an arrogant manner, there are many reasons to not rebuild NOLA in its current location, except for protecting the areas that did not flood during Katrina:
1 - the historic reason for the exact location of the city - an easy portage to Ponchatrain - is no longer necessary.
2 - much of the city is now well below sea level.
3 - and the entire region will continue to subside, meaning that we will be in a non-stop battle to keep levees high enough.
4 - we are in a major hurricane up-cycle that will last for at least two more decades.
5 - and the main reason - sooner or later, the Atchafalaya will become the main channel for the Mississippi - leaving NOLA stranded along a brackish slough. If we are gonna spend 200 billion in your state, let's spend it once to deal with that potential disaster as well, and move the port westward close to where the Atchafalaya branches off the Mississippi and goes to the Gulf. Sooner or later, Old River Control is gonna fail. Best we be ready for it.
That's my opinion, and I've stated that since Katrina hit. But as long as folks like you have the attitude that you have, good luck getting the tax dollars to carry that out. Which leads to reason 6:
The same corrupt hacks that helped create this mess are the ones asking for all that money.
Thanks for the reasons "why" to let New Orleans rot. Now how about the reasons "why" to save New Orleans?