I know there are bachelors degrees that are essentially professional degrees (engineering is the most obvious to me), but most people do not work in their "field of study." The traditional point of a bachelor's degree is not to be a professional degree, but to show a level of competence evaluating and thinking through problems. It's training the mind, not teaching a specific skill. That is true of the hard sciences almost as much as it is true of the liberal arts.
I have a great deal of respect for engineers--two of my immediate family members are engineers--but studying the liberal arts has a long history of preparing people for successful careers.