In the 70s it was restricted to the Midwest because of limited production capacity. The goals for the entire country were cleaner energy and reduction in dependence on oil purchased from enemies killing Americans. What additives do you consider acceptable? Why not use something easily renewable made in America?
Which demonstrates by the rest of the country, it wasn't required as a lead replacement.
What additives do you consider acceptable?
It doesn't require additives. The gasoline itself through refinery process can have enough 2,2,4-Trimethylpentane and the like to not require additives.
I have no problem with ethanol used in the free market. I have a great problem with a government mandated ethanol because the people won't choose it on their own.
A Balanced Approach to Octane Replacement
http://www.unep.org/transport/pcfv/PDF/BalancedApproach(Lee-Chook).pdf
Lots of options exist