There are a lot of reasons to ask these types of questions. Many will say "cultural fit" or "see how think on your feet" or even "get insight as to how you think and give you a chance to explain why to see your thought process.
I'm sure there are some who will disagree but I see this as a psychological power play, pure and simple.
Something I try to tell everyone looking for a job is to remember that you're approaching the company as equals. They want to make sure that you are suitable for the position and the company but so many forget that it is equally as important to make certain that the company and position is suitable for you as well.
Too many candidates treat an interview like it's an interrogation. They present themselves before an authority for questioning and then subject themselves to that questioning. Smart people encourage you to have questions for them to show you're interested in them but it's more than that. You are interviewing them too. Never forget that. And that's why I say that you're approaching prospective employers as equals because at that point, you are. You're trying to determine (at a minimum) whether they are deserving of you submitting yourself (to a large degree) to authority.
That's why I believe it is a psychological power play. They want to throw you off balance. It's manipulative and very one-sided but for some stupid reason, candidates accept this as, if not normal, allowed.
Still not convinced? Try doing it to them. Have a couple of "silly" questions prepared ahead of time and when it's your turn, pop one. If you're interviewing with someone who asked you something about what color of crayon you are, ask something equally silly:
- If you could undo one event in history, what would it be?
- You're the President and aliens have come to you saying they could cure one disease that isn't AIDS or Cancer. What disease do you cure?
- You have 3 people who are equally qualified with the exact same seniority and only have budget for 2. Whom do you let go?
I'm certain there are some interviewers who will be amused and see it as "turnabout is fair play" and will try to answer it. Most won't. That's because they don't see you as equal in the process. They see you as someone to be tested and judged.
That is why I see it as a power play. They're putting you in a position that is completely one-sided. It's making you jump through hoops simply because they can without considering that they're being evaluated as well.
We have for some reason come to accept the notion that it's acceptable for a prospective employer to put us in a situation solely to see how we react under pressure. Why? In deciding on a physician should we fake a heart attack so see how they react? The only person who gets to put me in a high pressure situation is the person who's paying me.
If you ask me one of these silly questions in an interview, I'm leaving. If pressed I'd tell them that the interview process has told me all I need to know about the company and it wouldn't be a good fit.