Cost vs. benefit
Millions of people live in Florida in houses that are not hurricane proof. Most of them survive each hurricane. If you price these millions of people out of the housing market, what's the point?
I could easily design a house that would survive a hurricane, flood surge, and other disasters. I sure as hell couldn't afford to build it.
One wonders what the building situation would be if insurance for disaster-prone areas wasn't heavily government subsidized...