dutch watermanagement engineers CAN most likely do something about this incessant flooding
They (the Army Corps of Engineers and the Netherlands Ministry of Transport, Public Works, and Waste Management) apparantly signed an agreement last year to share information, cross-train, etc. so maybe something will come of that. The ACE isn't exactly new to this thing either you know.
they've stopped frigging BANGLADESH from flooding
As best I can tell they're working with Bangladesh to try and reduce the flooding, but they certainly haven't prevented it. Much of the country flooded again last year. Bangladesh appears to be like Louisianna on steroids -- three large rivers coming together at a single delta, plus cyclones. They have very similar problems, although Bangladesh's are on a grander scale with fewer resources available.
I have absolutely no doubt that the Dutch could help -- as you say, it's largely a question of how much money do you throw at the problem?
Eventually a hurricane is going to hit land and simply kill the majority of people living in that state
Er, well... they get hit by hurricanes a lot, and the majority of the state isn't below sea level (merely very swampy). The worst case scenario for NO was a direct hit by a Cat5 -- which didn't happen this time -- and the estimate for that is 60-80k dead; mostly due to people who will not or cannot evacuate the area. There's really very little you can reasonably do to protect against something like that except to warn people to get the hell out. Which is exactly what they did this time.