The idea that building expensive marshlands is a substitute for a higher and stronger levee is typical enviro nonsense. Unfortunately, even the Corps of Engineers is now so infested with the enviros that funds are steered to eco-"restoration" instead of things that might actually protect human lives and property.
It's the USACOE that has been the problem all along, and we've seen that their approach doesn't work. Look at the shoreline work all up the East Coast...50 years of beach replenishment projects without a single one lasting even HALF the promised lifetime. It's the laws of physics...until you have the antigravity machine developed, you're arguing against reality.