metatag_metatags_save() ignores $langcode argument

The metatag_metatags_save() function has a $langcode argument that used to be used to indicate which language the values would be saved for. However, when the language handling was changed in 1.0 the argument became redundant. The question is - should we break API compatibility by removing the argument and just state categorically that all values passed into the function will be saved regardless of language, or change the function so that if the value is passed in then only that language's values will be updated? Either which way, it's certainly a confusing point in the API.