A bigger part of the corn syrup thing was basically coincidence of timing - it came out right at one the cyclical peaks of fat vilification. So products were reformulated to have less fat (and often less salt), and surprise surprise, they tasted like crap.
I should add, that cheaper corn also makes the things that eat corn cheaper. That doesn't mean those things are healthy.
The power structure / status quo is based on stability. Hunger / starvation of the masses tends to bring about instability. The point is, the food system is NOT driven by health (of the masses or the environment for that matter). It's driven by Food X's ability to starve off starvation (and associated unrest). That is, just because you're eating what's been normalized doesn't mean it's ideal for your health.
Cheaper === more consumption. That's basic economics. The corn subsidies drove down the price of that sweetener and in turn those (mostly unhealthy) products feel in price. *And* it became attractive to use in other products.
Yes, of course. There are other factors. But that doesn't diminish the fact that tax dollars are used to make the taxpayers unhealthy.
