fannie freddie

Much of the discussion I've seen on Fannie and Freddie has involved wiping out the equity and/or bailing out the debt, all in the name of protecting the housing market (and the economy that relies heavily on the housing market). I don't understand why the second (protection) is so closely linked with the first. As Warren Buffet did with bond insurance, why couldn't the government set up a new entity to buy and package mortgages and let both the equity AND debt holders of Fannie and Freddie bear the pain? It's not as if no one knew the two companies weren't rotten to the core. Unless the debt is so immense and widely held that a writedown would cripple the economy.