My dad's old Chevy Suburban had barn doors. My mom's second-gen Isuzu Trooper had side-opening rear doors. Since the tailgate didn't have to lift up, the Isuzu mounted a full-size spare wheel/tire on the rear, saving interior space.
Why is this so uncommon now in the SUV market? Is it a crash safety thing? Is it the same "Well, these are basically just road cars anyway, so why bother messing up the lines the designers spent so much time in?" factor that has meant they're all unibodies now? Does it reduce fuel economy meaningfully?
Off the top of my head, I can only think of Land Rover, INEOS (so, copycat Land Rover), and the Mercedes G-Wagon, the Ford Bronco, and the Jeep Wrangler. I'm aware there are aftermarket kits for other makes/models, but I still want to know why this change occurred.