Why do so many people think bio-diesel and E85 are the answers to our fuel problems?

The cost (monetary and energy expenditure) of bio-diesel and E85 is about 25% above that of petroleum based fuel sources. We're already seeing a rise in cost for corn, soy, and sunflower containing products. Do you really think that these bio fuels are the answer, or is it possible to come up with a more realistic energy source (like hydrogen) that isn't so costly in terms of energy use and destruction of biom?