If an event in your neighborhood kills one of your neighbors, what amount of money is appropriate to spend to prevent the next death?
Let's say you have overhead power lines and one of them breaks in "the storm of the millennium" and kills a neighbor. Is it appropriate for the government to spend $400,000 to bury all of the power lines in your neighborhood to prevent the next death? Nobody wants to put a dollar amount on a human life, but there's always the consideration...
How likely is the next "storm of the millennium" if this was the worst storm in history and the overhead lines have weathered all previous storms?
What's the opportunity lost by spending that $400,000. What if it could save two lives for half as much by putting up two traffic lights at the entrance to the neighborhood and now those funds are going to burying the cables.
Are there alternatives? After all, in this case you usually have quite a bit of warning that the power line is going to break. Can you improve your early warning and/or your evacuation training for much less?
What other impacts will the buried power lines have? Positive or negative?
In short, governments often make snap decisions in the wake of a disaster that they don't even necessarily expect will ever come to pass.
Lastly... let's give the people of Japan some credit. As much as I wailed at the time that people here were focusing so much attention on radiation that was unlikely to kill very many people (while hardly even discussing the tens of thousands of dead and missing from the earthquake and tsunami)... it's also important to point out that a 2004 earthquake off Indonesia and another in 2010 in Haiti killed hundreds of thousands of people. The difference is because Japan actually does a very good job at these things. There is no amount of money that can be spent to ensure that Mother Nature wins no battles.