I'm actually surprised that it has taken this long for USPS to come up with their weight+dimensions+cubic inches=total shipping cost. I'm a licensed customs broker working in international freight. For years airlines, steamshiplines and truckers have charged based on weight and space. The easiest way to explain it is as follow, what weights more 100 pounds of lead or 100 pounds of cotton? They are the same, but cotton will take up more space than lead, hence it will be charged a dimmensional weight. After 9/11, the airlines have come up with ways to charge more $, on top of that you have to add the high cost of fuel. USPS is just passing the cost to us the consumer.