If you converted all of Dinoland to "South America" and remade Dinosaur as Indy, you'd still be deviating from the parks theme, but not too badly, especially if you added a more animal-centric walk and second ride. You'd be entirely eliminating dinos, which are really popular, from WDW unless they immediately announced a whole new dino area. If Uni was smart, they'd immediately expand Jurrasic Park and corner the Orlando dino market.
I strongly suspect that WDW doesn't want an Indy ride in a "South America" land, they want a full Indy land. That's the logic of the modern theme park. And that wouldn't fit.
Look, Indiana Jones, like GotG, can support a big, lush area and WDW has room for it in places that are thematically appropriate. Shoehorning it into existing structures is just nuts.
Hey, you know what would have worked at MGM? Instead of a cheap n' chintzy TSL, build a nice fancy Indy land to go with SWL. Then the MGM makeover would actually fix some of the parks problems.
