Any good dog owner pretty quickly learns what a dog's bark means most of the time. Also, I'm not sure a bark alone without the body language to go with it is really all that helpful. I can tell so much more from my dogs' body language including things like when they're looking for a place to poo on a walk as opposed to just walking around and sniffing stuff.
You also would be a lot less likely to know that one of my dogs is super angry if you didn't know that her hair stands up like she has a great big stripe down her back when she does.