We've heard that song before, haven't we? We've heard it with some variations, but the theme is the same. Perhaps the same problems create the same theme - with some variations. Even the variations do not nuance the repetitions enough to make us pay attention, finally.
If it were not for two things, Malachi's oracle of God could be passed by as "just the same old thing." The oracle is from God. Secondly, it comes because God insists on keeping his covenant. He simply cares. There it is. Do we wish to consider the alternative - a God who does not care?