And when exactly what they were warned would happen happens, what do the enviroweenies say?

"The big green groups that got invested in biofuels are tacitly realizing the blunder," said John DeCicco, a research professor at the University of Michigan Energy Institute who previously focused on automotive strategies at the Environmental Defense Fund. "It’s really hard for the people who really -- shall we say -- hate oil viscerally, to think that this alternative that we’ve been promoting is today worse than oil."
Surprise!

The Natural Resources Defense Council used a 96-page report in 2004 to proclaim boundless biofuel benefits: slashed global warming emissions, improved air quality and more wildlife habitat.

Instead, farmers plowed millions of acres of prairie grasses to grow corn for making ethanol, with fertilizer runoff contributing to a dead zone in the Gulf of Mexico. Scientists warned that carbon dioxide emissions associated with corn-based ethanol were higher than expected. And alternatives using switchgrass, algae and other non-edible plant materials have been slow to penetrate the market.
They've been 'slow to penetrate' because they either don't work worth a damn, or are so damned expensive nobody wants to touch them.  But keep hoping.

Even the NRDC that once lobbied for the RFS bemoans that "the bulk of today’s conventional corn ethanol carries grave risks to the climate, wildlife, waterways and food security." In NRDC’s "OnEarth" magazine, an essay headlined "Played for a Fuel" argues that corn-based ethanol isn’t sustainable because it requires "huge amounts" of water, fertilizer and land.
Which is EXACTLY WHAT THEY WERE TOLD WOULD HAPPEN.  And they called the people giving warnings luddites, and Haters of Gaia, and shills for Big Oil, and anything else they could think of.

So: just like warned, when the enviroweenies crawled into bed with the corn lobby, it meant lots more land being plowed, less food corn being grown, lots of resources going into growing this stuff for a fuel that damn few people wanted, and now they're all surprised that it happened.

Geniuses, I tell you.  And some of them just can't admit it.
Some biofuel proponents say alternatives are worse.

"In the absence of ethanol, your next barrel of transportation fuel is going to be coming from petroleum from fracking or tar sands or deep-water drilling," Bob Dinneen, president of the Renewable Fuels Association, said in a phone interview. "So you sort of have to assess ethanol in the context of what its replacement would be, and quite frankly, by that measurement we are the stone-cold winner."
Only if you count all the money to the corn lobby, and the food riots and so forth as 'winning'.
And the other people claiming this is a victory are just as stupid, or just as/more corrupt:
Jeremy Martin, who leads fuel policy for the Union of Concerned Scientists’ clean vehicles program, said the RFS has become a scapegoat, unfairly blamed as boosting demand for ethanol that probably would have reached current levels in gasoline even without the program. He casts the climb in ethanol use and the expanding footprint of corn that accompanied it as a "a one-time transition" as the U.S. fuel sector made a big shift, essentially adopting a 10 percent ethanol blend as the default gasoline.
The demand would NEVER have reached this level without you, and the corn lobby, and your paid-for congresscritters shoving it down our throats in the name of 'saving Mother Gaia(and lining our pockets)'.  'Default gasoline' my ass.