Your question got me wondering about that, so I pulled out David Thompson's book and here's what he says:
The juice from kafir limes is very pungent and should be used cautiously. A little gives an alluring perfume and yet has a surprisingly pervasive taste. Too much and it overwhelms every other flavor in a dressing, giving it a soapy, bitter taste. When kafir lime juice is used, it counters robust or coarsely flavored items, such as pork liver or meaty fresh water fish. Occasionally, the juice is used with salt to cleanse and bleach ingredients like offal before blanching.
He also mentioned that the frozen variety is not good in dressings or marinades, but only used for its bleaching qualities, and must be well rinsed. In the book, he only has 3 recipes that use the juice and only in very small quantities (tsp - tbsp). Of course, many of his recipes use the leaves & rind.