The whole plant isn't wasted. They grind up the whole plant and use it for silage.
As a person with a corn allergy...you'd be amazed at what they put corn in. I swear they hire rocket scientists to market their product, it's not your average "hey gluten is in a lot of stuff" product, it's in EVERYTHING. A huge amount of plastics & packaging are now made from corn - plastic bottles, plastic utensils, boxes, linings, etc. Then you break it down into edibles, which splits into corn products & corn derivatives. This is just a
small list of hidden corn names in the wild:
http://www.cornallergens.com/list/corn-allergen-list.php
Dextrose (anti-clumping) in your salt? Corn.
Citric acid in your OJ? Corn.
Ascorbic acid in your apple juice? Corn.
I could go on forever. The problem with repetitive exposure to common allergens, grains in particular, is that it can make you go from normal to allergic due to over-exposure. And in the case of corn, you don't even realize how much of it you're eating. It's like hidden sugar and how that sugar is causing diabetes & heart disease because people don't have a clue how much they're actually consuming on a daily basis.
I'm fortunate that I'm not at the anaphylaxis level for corn, but I do know people who are - they have to make EVERYTHING from scratch, including soap & lotion, use metal silverware, etc. They can't drink out of plastic bottles because they start swelling up. While they don't have good allergy tests to identify it yet, the number of people getting diagnosed has been growing like crazy, and I think it's only going to get worse over time.
And strangely enough, most other countries are doing a great job regulating GMO's, food additives, manufacturing agents, etc., but here in the U.S., our political system is so tied into third-party funding that I doubt we'll ever get to a reasonable level for responsibly handling actual food ingredients. I'm not against all GMO's, but it's pretty ridiculous the amount of control that private companies have over our food supply, which makes it extremely difficulty for the minority of us who have to deal with things like food allergies that don't currently require any sort of labeling on the package.