It's worked for us (relatively)...
"The question is, if we're not getting any health benefits, then why continue to promote ethanol and other biofuels."
How about because such biofuels are supposedly much better environmentally than fossil fuels? I mean, the CO2 from the plant you kill today for fuel will be re-assimilated later when other fuel plant grow. Not all of it, but a fair bit. With fossil fuels: probably zero.
In Brazil, we've had already almost 30 years experience with ethanol derived from sugar cane. I'm not in this business, but there are some things I heard about it there. There was a time, in the mid 80s, when more than 50% of the cars ran on ethanol. The octane is higher indeed, but the gallons/mile is a bit worse. Since ethanol was (and is) quite cheaper than gasoline there, it was worth it. But then oil prices fell... and ethanol cars became much less fun, and slowly retreated to very low numbers. Now, with oil prices spiking, they are trendy again, with one important difference: now most if not all new cars are "flex fuel", which means they run on either gas or ethanol or whatever mixture of those. You can have half a tank of gas and then top it with ethanol if you're short on cash, for example. Millions of cars here in the US are flex fuel too, and people just started noticing that recently (because they started putting a little sticker saying so in the back of the car).
Of course the fleet in Brazil is much smaller (some 10x last time I've seem any numbers) than the one in US, but nonetheless only a single smallish state (São Paulo) produces almost all the ethanol we need. Plus the largest orange crop in the world, and much more. Check on your box of Minute Maid. :-)
Now, if those fast neutron fission reactors would become reality, most of the problems of current nuclear tech would just go away. Oh well, new problems would sure arise...