Because ethanol does more bad things that just eat fuel lines and O rings. It attracts and holds water which can be very corrosive to metal parts. In 2-cycle engines, it acts as a cleaner and removes lubricating oil from the pistons and cylindars. It effectively reduces the amount of energy produced by a given volume of fuel (ever notice that your gas milage in your car is much less than when you were able to get unpoluted gasoline?) It increases the cost of food (corn going to produce ethanol is not available as food or to feed livestock producing your baby back ribs) and has increased the presence of malnutrition in third world countries. The subsidies paid to corn and ethanol producers has helped to increase the national debt. Should I go on?