It's not the only solution I can think of, but it's the only practical one. Sure you could build giant sea walls around the area or bring in land and start literally raising all the buildings above sea level (similar to what Chicago did in the mid 1800s), but you are talking billions of dollars, maybe hundreds of billions. Once you get into that situation it just makes sense to move everything upstream and perhaps only fortify key infrastructure like ports until even those pieces have to be relocated.
The army corps of engineers is not given the option of not trying to save New Orleans. People in government tell them to go build levees and protect the city from flooding and they do the best job that they can, but they are fighting a losing war. The time to introduce relocation assistance programs is now, so you spread the cost and process out over many years; otherwise, you are going to just end up doing the same thing later, but it will cost more money and more lives will have been lost.
The army corps of engineers is not given the option of not trying to save New Orleans. People in government tell them to go build levees and protect the city from flooding and they do the best job that they can, but they are fighting a losing war. The time to introduce relocation assistance programs is now, so you spread the cost and process out over many years; otherwise, you are going to just end up doing the same thing later, but it will cost more money and more lives will have been lost.