Well I myself feed organic corn (non-GMO) and soy free feed for a large variety of reasons. Because I can, not everyone can afford it but I can and that is what I want.
I want it for many of the previously mentioned reasons but I'll state mine.
1. I don't like GMO, I garden and I think that GMO is killing off heirloom sustainable plants especially if they are wind pollinated like corn it can be hard not to get contaiminated even if you are growing your own heirloom corn. Monsanto is relentlessly pursuing farmers and through different corporations under their umbrella own a huge portion of the seed market which will make it harder to get natural products.
2. I don't like GMO because they are used specifically to spray acres upon acres with roundup which I don't want on my food right before harvest anyway, don't care how safe the company says it is (and the FDA agrees without independent studies) same company that said DDT was safe and agent Orange by the way. We can totally trust that Round up which will kill all plant life it touches (except this corn) won't hurt us. Or bees, which in recent years have seen a dramatic decline and are necessary to life. Or butterflies which are just one of my favorite insects.
3. GMO soy and the demand for Soy in general is literally killing the rainforests. Brazil is one of the main exporters of soy and guess where they are getting all that crop land from. You guessed it the rainforests.
4. Soy has natural hormones in it. I try to avoid large amounts of soy period as too much of our food is hormone regulated now. I also believe soy is better when fermented like tofu or soy sauce. Not all the soy solids and crap stuck in every processed food you can find.
5. Soy would not be a natural chicken food.
6. I'm getting to the age (whatever that is, it's different for different people), that I care what I put in my body. I am not totally doing anything healty, yes I still eat out, no I'm not a vegan (of course I believe meat is good for your body). I can easily make my eggs healthier for myself by feeding good feed and letting them free range and providing veggie when available. I have no doubt that my eggs are nutritionally superior to the grocery store and I know the taste is better.
7. By feeding them Organic, Soy-Free feed I get extra money that offsets the extra cost so it doesn't even cost me extra except when I raise broilers for myself. ($3/dz)
8. All the ingredients in my bag I understand or can look up and understand. I don't like any bag labeled "Grain products, plant protein products, processed grain byproducts"
I like to know what is in my food/feed.
9. Purina is a very large company and I don't want to wonder where was this bag made. Too much stuff is now made overseas particularly China, including food, pet food and ingredients for food and pet food. China is just not regulated right now and too many mistakes are coming out of there. Also many of these countries do not hold to our pesticide/herbicide standards so you don't know what's in some of the large feed company bags. Remember the dog food that was killing dogs? Or the baby food that gave them gallstones? Or the toys with lead paint. Or melamine being added to anything that was going to be protein tested?
10. GMO corn has been so popular that now they want to upgrade it so the corn grows BT in the corn. I like BT as an organic control of catepillars, but I want it on the outside of my food so that it can be washed off not on the inside. I also would like it added only when needed not 100% of the time. I love innovation for most things. I dislike GMO and don't think it has been tested enough to be called 'safe'.