Besides everyone knows your safer on a ship than on land in a hurricane. At least the ship can move out of the path.
I agree Dave it certainly wouldn't make sense to take all the ships out of the Caribbean. There's a large market of first time cruisers and the shorter Caribbean cruises have appeal to that market. Also Caribbean cruises are more affordable with driveable ports. For those that do fly in, it certainly is more affordable than Alaska or Europe.