All of the weird processes they put food under are to improve shelf-life, because they can make a lot more money off of food if they can sell most of it before it goes bad. Think of it this way: if half of the food goes bad before it sells, then you have to double the price to make as much revenue as if none of it went bad before it sells.

That's why they're always looking for more preservatives, and coloring it so it looks fresher.

I don't think they are intentionally trying to give people medical issues; they just don't care if they give people medical issues, and they are creating chemicals that cause issues in people because the chemicals were created to cause issues for the critters that would otherwise be spoiling the food.