Quick Question

Dutch plant idea of Tulip Island

I have a picture that I may upload, but the concept is pretty clear.

Thing is, while I can see how it can relieve pressure on overcrowded cities, how does and island protect the coastline from rising sea levels? Some storm surge effects maybe, but 'levels' will just find a way round, surely.

Also, other than a pretty satellite picture, what possible benefit does this design confer?