Should such a drastic move be taking place now, before the model conclusion say it will be underwater?
That based on the fact that the 1,5C goal has long since become untenable without drastic action, which is presently not taking place. -
The automated barrier closure was triggered by the combination of a winter storm and high tide pushing in a lot of extra water up the river. Add to that saturated rivers draining essentially most of Europe's rainfall and you get a picture of what is routinely dealt with there. The rivers are actually a bigger issue than the sea. Forested areas that used to absorb a lot of water are vastly reduced in size. More extreme rainfall now flows straight into the Rhine and Meusse rivers, which both exit where this barrier is. The solution for this is not more dikes but flood zones.
Other parts of the world are much less ready for higher water levels. Florida for example is particularly poorly prepared for even modest water level rises and has much less extreme tides; so the averages matter more. There just isn't a whole lot in terms of sea defenses and other infrastructure. Any storm is likely to push a lot of water in. Combined with even modest sea level rises that means there just is a lot of property at risk.
What might become a problem though, is flooding of rivers. The Netherlands is a river delta for a large part of Europe. Melting snow in other countries gets transported to the North Sea by several large rivers. If (when) sea level rises it gets harder to get rid of al that water fast enough. Perhaps we have to dam up rivers until low tide and let it all out at once, for example.
Still, we are on top of it and there is still enough time to build higher dams and dikes. We'll survive.
A substantial part of the Netherlands is already below sea level, even without climate change. Half of the country is less than a meter above.