No, it was a perfectly fine question IMHO. it is a broken incentive - it is expected that you design complex systems regardless whether they are useful or not. Try to interview for the role you have to fill, nor for a role you a dreaming you would love to have whenever you're Google2.

If the interview wants you to think about stuff that never happens in your role, I think it is a sign that in your role, you're expected to solve the problems like in the interview.