No one really believes that the Renewable Fuel Standard, or that ethanol mandates in particular, are a good and sound policy. But they have survived for years and years because it was believed that you could not win in Iowa if you ran against them, and you can't be President if you don't perform at least decently in Iowa.
Ted Cruz challenged all that directly. For doing so, he was opposed tooth and nail by Iowa's governor-for-life Terry Branstad and his powerful ethanol lobbyist son. He ran against Trump, who cynically called for increasing the ethanol mandate. And he won, and won fairly handily in the final analysis.
If Ted Cruz can win Iowa while opposing ethanol mandates, that means everyone can. And that means our country doesn't have to be saddled with this terrible policy any longer.
So regardless of who you favored tonight, Ted Cruz's win in this caucus was a huge win for America.