A happy animal is indeed a tasty animal. That's why we raise cattle in dry pens (away from predators) with abundant fresh water and feed them carefully formulated food twice a day. Our cattle get better dietary planning than I do; they don't eat pure corn (as the term "corn-fed" might lead you to believe), they eat a mix including alfalfa, grass hay, corn, barley, silage, cannery surplus apples, oats, molasses, and other ingredients. The fact is, big or small, any cattleman is going to try and keep the conditions as good as possible. If your animals are standing in 2 feet of mud and eating moldy hay, they're not going to produce and you're not going to make money. Also, nobody goes into the livestock business hating the animals--we who grew up on farms probably have a better understanding and empathy for livestock than your average city-dweller, and we want to act kindly toward them.
As for grass feeding, you want to know something? One of the biggest grass-fed beef producers back home only eats corn-fed beef. Corn-fed beef is more extensively marbled and more tender. Like organic produce, grass-fed beef is a niche market for people who think something tastes better because it has a crunchy image and damn the price/scalability/sustainability.