Many of the reasons I hate corn are summed up in this article by Michael Pollan. You should read it, it's really interesting, but basically Pollan lays it at the feet of the US Farm Bill. The US government gives ridiculously high incentives to farmers to grow corn (and wheat and soy), paying them a set price per bushel rather than any kind of market rate. This leads to a massive over-supply of cheap corn and soy, and since these are used to feed animals, cheap meat.
Why? Because it's an easy way to feed money to voters in low population density areas. It's a quick sop to "supporting our rural heartland" and "feeding America".
But we don't actually need all this damn corn! "So what" I hear you cry, "so there's a lot of cheap corn, don't mean nothing to me". Well, I'll try to tell you why I think it does in the next rant.