This is not relevant for the political side of the question, e.g. it would not be possible for a citizen on its own to judge whether the merits of a treaty. Say, your senator campaigns on withdrawing from the Iran deal: how are you supposed to assess this position if the deal was in third-party-language Pashto?

In addition, I can present the case of France, where judges must disregard laws that contradict treaties (the hierarchy of norms being Constitution > Treaties > Laws > Executive orders). Therefore treaties, even with no national law to implement them, have a direct effects on the law.