It’s mostly a win for world stability because it preserves, to a limited degree, the notion that you can mutually agree, put it in writing, and count on the other side fulfilling its obligations as long as you do.

Nobody with half a grasp of reality doubts that Iran was fulfilling its end of the nuclear deal. It’s entirely unclear why China, or North K, or really anybody should trust the US Government in the future. That means one of the arguably most important tools to avoid armed conflict was entirely eliminated from the US arsenal. What makes it even worse is that there just wasn’t any reason to do so, beyond some egotistical jingoism. Saudi Arabia is far worse in almost any observable category.