I have to admit a bias: I hate movies that make fun of the South. My take is this: Movies (and television shows) are produced on the East Coast (New York) and the West coast (Los Angeles).
Since most people don’t find pleasure in making fun of themselves, the East Coast and West Coast collectively look for someone else for their comic relief. The South is an easy target. (So is the Midwest, but I don’t live in the Midwest… so those are kinda funny). (joke).