The issue is that the future career path is less obvious than many other disciplines.  As others have noted English, History, Philosophy and others are often precursors to future degrees notably Law.  A good portion of the humanities, social sciences and even the sciences were never intended to be direct outlets to careers.  Some disciplines just have seeming more obvious paths or mesh well with identifiable job titles.  Although that too can be source of frustration - like assuming that everyone with an accounting degree files taxes for a living or that everyone with a law degree plans to be a trial lawyer.

It seems to be that if you feel your degree is being undervalued that perhaps you haven't done a very good job at articulating your educational background and career aspirations.  If you can't explain it to a friend or acquaintance how on earth to you plan to communicate those skills to a potential employer?