AGREED. with the current gas prices my cost per mile is less per mile with E85 than 87 octane. If we had E100 ( or whatever it would be called) i'd imagine the price would be even lower.
IIRC, straight ethanol does not have the cold-start properties necessary for typical ICEs. That's why it's blended with gasoline.
I also recall reading that an engine designed to run purely on E85 (i.e., not flex-fuel) can be more economical to operate compared to one designed to run anything from E0 to E85. The catch is that E85 is relatively uncommon so a straight E85 vehicle wouldn't sell because getting fuel would be difficult. I could be mistaken on some of that though.
Fuel infrastructure is a limiting factor in adoption of any new engine fuel. Hydrogen, E85, electricity, and unicorn farts all lag behind gasoline in terms of where and how fast a vehicle can refuel. My guess is that it will take significant government intervention to change that. I.e., the fed .gov will have to mandate the construction of alternative fuel station and/or provided significant financial incentives (grants, tax breaks, etc.) for them to even begin to approach the ubiquity of gasoline stations.