No doubt on the replacement cost issue. Most older homes have ordinary windows. When you rebuild you have to use windows built to a standard developed after Hurricane Andrew. The difference in cost between the two is astronomical and not covered by most replacement insurance policies I've been told.
You're right! Even when we added an addition to our home, we had to upgrade every window in the house to meet the new code. We couldn't just put "code" windows in the addition, every window in the house had to be replaced including the garage window, LOL.