Using 'surplus' corn..etc...for bio-fuels to stretch supplies might be fine, but growing monoculture crops IN ORDER to build dependencies on them is a serious error. Brazil has done something like that, but at increasing cost to the rain forest.
We already have monoculture in some forestry...with resultant problems in species diversity. Monoculture is highly dangerous in another way also: any disease or drought or pest infeststion can wipe out the crop....and we know what excess pesticides can do.

Better be careful.