Hmmm, I wonder if it had anything to do with the limited food preservation techniques at the time? /s
In the "A Chef's Life" holiday special, Vivian had a guy on that demonstrated how to make corned pork using parts from a freshly killed pig.
Salt and vinegar were the preferred preservation methods that came over with the colonists in the early colonial era. Sugar was expensive to the point of being a status symbol then, and not always widely available. Several southern dietary habits go back centuries like this salt cured ham. Very sweet desserts and sweet tea, for instance. It was a treat to have sugar to even make a dessert or sweeten your tea. Then sugar became more of a commodity. Sugar cured ham became more popular. The traditional desserts, once sort of status-ey and only for special occasions, became widely available.