Another wonderful side effect of which I haven't heard much discussion: carburated engines do not like 10% ethanol. Lots of outboard motors are carburated. I've spent more time than I want fiddling with the idle and lean adjustments, trying to keep from stalling while not planing at "idle". I watched some poor guy try to motor his sailboat away from his mooring, and have the outboard die repeatedly. He ended up drifting into several other moored boats while he tried to restart the outboard. He finally got the mainsail up, and managed to sail out of the mooring field, but it didn't look like much fun.
A lot of older power boats have built in tanks with fittings that aren't designed for E-10. The choice is rip out the tanks, (expensive) or wait for that fine day when the boat goes up in a ball of fire from the gas leaking into the bilge (life threatening, and even more expensive). Maybe it'll just be easier to torch it off yourself, and collect the insurance.
Who is ethanol supposed to help besides ADM and Cargill?
The politicians re-election funds.