Physical fitness, which a badass possesses above an average individual, tends to come in handy when doing any common physically demanding tasks (ie, enduring inclement weather, moving furniture), when you need to not be sick, and when you want to slow your degeneration into a decrepit old man/woman by as much as possible.
People tend to idolize badasses more (see: Arnold Schwarzenegger, Chuck Norris, Georges St-Pierre). Being badass is a sign of character. It's an accomplishment, whereas beauty is often something that is handed to one upon birth (or paid for with plastic surgery)