I agree with everything you said, but we have to ask other questions (to be fair) if we look at your questions.
Sure it should, and we know that the answer is a plant from the ground, but if we know that corn is not healthy or less healthy, then we need to stop it from being put out period. If we allow people to have it in their backyard it is no different than in the woods. Also the other issue (whether healthier or not) is people plant food plots to shoot deer on... so maybe it is for herd health too, but ultimately that is where you set up to shoot deer, so you are using them (I am too) to shoot deer. It may be the healthier option, but without stopping it all together, people that don't have equipment, or money for seed and fertilizer, etc. should be able to put it out until they say it is bad and we are going to cease the whole practice.
I would use the same logic of making it illegal for everyone and all purposes to comment on your MSU study. If we know it is bad and the wildlife is the focus, then stop it all together. However, it can't be bad for me and not for thee though when it comes to hunters and nonhunters.