It's because of the farm lobby shoving it down our throats.Ethanol actually is a very good, clean burning fuel. It has a very high equivalent octane rating in the 110+ range. The down side is our engines are not set up to burn ethanol. If we had high compression engines (cranking compression of 220PSI+) and all of the fuel lines and related equipment was compatible It would be excellent. But, we don't. Some of the cons are the problems with storage and transport. Also it contains about 60% as much energy as an equivalent amount of gasoline.
My feeling is why are we burning our food stock in our combustion engines when we are awash with petroleum? Also due to the decrease energy content, if gasoline was $2 a gallon then ethanol would need to be about $1.20 a gallon.