I wouldn't call myself a fan of this genre, but clearly a lot of modern TV executives are, if the proliferation of hillbilly-themed TV shows is any indication. Basically that's the gist behind the film genre as well -- hillbillies are funny and weird, let's mock them mercilessly.
In fairness, in film it's less about how funny hicks are and more about how they want to kill and/or eat and/or wear you. Filmmakers for decades now have sought to convince us that pretty much anyone whose home can be accessed by a dirt road in the American South is an inbred cannibal sex monster. You're going to be eaten, killed, or humped by literally everyone in the better part of at least seven states.
Deliverance might qualify as the most famous hixploitation movie of all, and it has the added bonus of giving the world the phrase "squeal like a pig," something we never knew we needed until we heard it that first time. If Deliverance doesn't qualify, then The Texas Chainsaw Massacre does, and you all know how that turned out -- damned hillbillies making people masks.
Shining Example: Cockfighter
I'll be honest, I'm writing about this solely for the name because it makes me laugh. I'm an adult. What's a hixploitation movie called Cockfighter about? Cockfighting. A guy who took a vow of silence and devoted his life to cockfighting. Hollywood doesn't make stuff like this anymore, and man, it should. The main character doesn't speak, he just wants his chicken to kill all the other chickens so that he can win Cockfighter of the Year. That's the real plot, not a joke one.
In the movie, the character sells everything he owns so he can keep cockfighting and also gives up his family. Has anyone in the history of ever been so committed to wanting to watch one chicken kill another chicken? Maybe Colonel Sanders on a bender, but other than that, no. Not at all.
Short of playing jug music and marrying cousins, there's probably no other topic that's more hillbilly than cockfighting to focus a movie on, so thumbs up to Roger Corman and the crew behind this film for really hitting a niche where it counts.
No, this isn't about Bruce Boxleitner, why would you think that? You don't even know who Bruce Boxleitner is. In a perfect world, it would at least involve Bruce Campbell, but I don't think he allows people to exploit him. That leaves Bruce Lee. Lee also would not allow people to exploit him if he had a choice, and he could have kung fu-ed the living hell out of anyone who tried while he was still alive, but this genre popped up only after his death.
How did such a bizarre genre come to pass? Blame the awesomeness of Bruce Lee and the stereotype of all Asians looking alike. When Lee became huge in America, kung fu movies exploded. Then in 1973, only just after the success of Enter the Dragon, Bruce Lee died. Hong Kong realized they'd potentially lost a massive cash cow, so they scrambled to replace Bruce Lee and keep the kung fu genre alive. Thus was born actors like Bruce Li, Bruce Le, Dragon Lee, and literally over a dozen other guys who all, from a reasonable distance, looked like Bruce Lee. And they made cleverly titled movies like Re-Enter the Dragon, Exit the Dragon, Enter the Fat Dragon, Enter Another Dragon, The Dragon Enters but Just the Tip, Backdoor Dragon Boogaloo, and I Entered the Dragon and All I Got Was This Syphilis. Some of those I made up.
Shining Example: Game of Death
I have to pick this as the best Brucesploitation film of all time because it actually stars Bruce Lee. This was the movie Lee was making when he died, and five years later it was rereleased with the same name and new scenes that featured a dude who wasn't Bruce Lee. They literally replaced him in his own movie and included scenes from his real, actual funeral. In the movie, Lee's character dies, so the filmmakers thought, "Welp, real Bruce Lee is dead, so footage of his real funeral will look extra authentic!" In Asia, tastelessness wasn't a thing until the year after this movie was made.
Other tragically flawed ideas included scenes in which Lee's character does everything he needs to do wearing a motorcycle helmet so you can't see his face and a scene in which Lee's character looks at himself in a mirror and they opted to use a cardboard cutout of Lee. It's cardboard.
Also noteworthy in that scene above, right at the two-second mark, you'll notice that towel on his shoulders isn't real. They cut in a scene from another movie and just added the towel to make the scene consistent with the overall shitastitude of the entire film.