This is based on the assumption, that nobody else crafts his own toolchain or modifies the existing code to accomodate for his needs better. If in any case you do not have the surrounding XML available (lets say stripped it away because you did not have the space on the harddrive, or the file got corrupted), you will need a fallback. And then you might want to pass a null value intentionally to tell the method: "Use whatever you find in the JSON".
I can live with the "In dubito pro *dump-provided-page-title*".