If a result is achieved form your reply and that result is used to make a determination on your suitability for the role then it is justifiable. Some of these seem like they have been added as a last thought to the interview in order to stir without just cause.
Whether these questions seem asinine, incredulous or plain stupid, at least they stir up polar opinions on the subject. There are very few bland, middle-of-the-road opinions from all the comments - this is commendable as open debate has been stirred.

Whether they are correct in being asked during and interview? You don't have a choice when you are on the replying side of the table - how you deal with that question should be particular to the job being applied for - a market analyst should give a different reply to a software developer or database analyst . Whether those questions are structured towards the job description is not to be debated in the interview, unless you are being recruited for a human rights lawyer position?