Corn in NC

I've seen/heard a couple of stories about what a bumper year this is for NC corn. Here is one. That's great. Here it says that most of our corn gets fed to livestock. Why? Is it not good enough for us? How good is NC corn? And why is it so hard to find in supermarkets even in season? Why do we import from other states when we have it here? Maybe it's just not very good?