It's the simplest thing to cause more pain than a man can possibly enjoy. Le Chiffre: 'You know, I've never understood all these elaborate tortures. However, imagining Pierce Brosnan getting a good testicle pummelling was almost fantastical in comparison - no 007 could ever have handled the sheer brutality of this scene as well as Daniel Craig. Effectively, it is the North Korean prison in Die Another Day, because as with any torture, the purpose is to extract information, or get what someone wants. There is just a naked Bond, tied to a chair, and Le Chiffre, holding a big rope with a knot tied at the bottom.
The most expensive scene in the movie is the collapsing Venetian building drama, but aside from the opening film noire scene, the Rope Torture scene is by far and away the most gripping of the movie.