Cliches aren’t a bad thing, they’re actually quite reassuring. Everyone enjoys the satisfying clunk of a plot fitting into the shape we expect.
It’s the same with writing – sometimes using the first phrase that springs to mind allows writing to read smoothly and invisibly. It’s kinder on the reader than a relentless attack of originality in every word and sentence construction. What we want is soothing predictability wrapped in something that feels real – an honest, authentic voice offering us ever so slightly new ideas in the familiar shape of a platitude.
Witless mixing of bad metaphors will always be annoying though, but that’s as much because it’s jarring as because it’s unoriginal.