To begin with, it’s “bated” as opposed to “baited”. “Waiting with baited breath” is clearly rather nonsensical. You’re waiting with your breath set as bait in a trap? Bated is an archaic, abreviated form of “abated”. So, “waiting with abated breath,” essentially means that your breath has lessened, or likely stopped, because you’re wracked with nervousness or fear. Essentially, you’re holding your breath. So another common idiomatic expression, for the sake of consistency, ought to have been phrased, “I’m not going to bate my breath,” when you don’t think something will actually happen. It’s weird how idiomatic expressions linger in…