I feed my chickens organic feed partly because I'm not comfortable with GMO crops. 80% of feed corn is GMO, so it's hard to avoid unless you go organic. I'm also a beekeeper and have seen the effect that pesticides have on bees - it's tough to keep bees alive if you live near a conventional farm or orchard. Some conventional farmers will spray pesticides early or late in the day to limit exposure to pollinators, but many don't bother - even the orchards that depend so heavily on pollinators.
I feed my chickens Countryside Organic feed, which I like because it looks fresh, all the ingredients are listed on the label, and I can see what's in it, ie, bits of grain and field peas. I ran out a few months ago and bought a bag of Nature's Best crumbles, which is the only organic feed available near my house. I didn't like feeding that to my chickens. There was no list of ingredients and it was ground down into tan colored crumbles. My chickens free range during the day, and during the growing season they get tons of vegetable scraps, but I still like their feed to be closer to a whole food than dry crumbled bits.
I personally think that organic food is healthier, that more fertile soil will produce a more nutritious plant than something grown in dead soil with petroleum based fertilizers. But if I couldn't afford organic feed, I'd still want to keep chickens. Keeping chickens in our backyards, even if they're fed conventional feed, seems a much more natural, sustainable practice than keeping chickens in factories that eat organic feed but never see the light of day.