Stony, there are a few reasons that souring corn is "better" than plain corn.
Firstly is that while pigs love stinky sour corn, deer and coons don't seem to like it. That keeps those animals out of the picture. In areas where the game wardens get upset about baiting deer, having soured corn lets them know your intentions aren't for shooting deer.
Secondly, putting soured corn in a hole in the ground makes them work for it rather than gobbling it up. If your intention is to hunt them then that gives you longer time on the bait station in which to shoot.
Thirdly, you already mentioned the scent thing. It tends to draw them in from further away.
Firstly is that while pigs love stinky sour corn, deer and coons don't seem to like it. That keeps those animals out of the picture. In areas where the game wardens get upset about baiting deer, having soured corn lets them know your intentions aren't for shooting deer.
Secondly, putting soured corn in a hole in the ground makes them work for it rather than gobbling it up. If your intention is to hunt them then that gives you longer time on the bait station in which to shoot.
Thirdly, you already mentioned the scent thing. It tends to draw them in from further away.