I believe the context matters: In a poorer economy where it's hard to find jobs it would be a dumb question as the candidate is probably applying everywhere to

I believe the context matters: In a poorer economy where it's hard to find jobs it would be a dumb question as the candidate is probably applying everywhere to make money and pay their rent. In a place where things are easier financially, the question would make some sense: there might be multiple options, many companies to work for and the candidate is not in immediate desperate need for money, so "why us?" makes sense.