Every time I read something about the U.S. leaving the U.N. or something calling for the expulsion of some state from the U.N. I am reminded of one simple fact.
As long as we are members, we have a voice. As long as even rogue states are members, they have something to lose if they are expelled. A voice... we have a means of putting our side of things out for the U.N. to consider. If we leave, we lose that lever. If we expel a state for whatever reason, the last method of even slight control over them is lost. If they have nothing to lose, they have nothing to explain and no reason to conform to U.N. protocols. These levers may be small, but they are better than nothing...much better.