The relevant bit in "Why do you want to work for our company" is the unstated "...as oppose to another." Ideally the answer is some property of the company that aligns well with the candidates ideals. But it presupposes that the candidate knows of some attribute that fits this frame.

A better question might be to make the company attribute hypothetical. Something like: "if you could propose a rule for all employees at the company where you want to work, what would it be." You'd definitely need follow-up questions and promoting, but it could be way more insightful.