You can test people's memory if you want to, but it doesn't seem like that was the original intention behind the question. I'd suggest giving people advance notice for questions like this so that they can look through their past work and pick out some interesting cases. That way you don't select for people who randomly happen to remember something interesting within 30 seconds, or (more likely) people who are good at making things up. Surely the real point of the question is to talk about something interesting that someone has worked on, not to administer an ad-hoc and unscientific test of their memory.

As for strong emotional experiences, it seems obvious to me that people will have a wide range of different emotional reactions to their work. None of these reactions is inherently better or more correct than any other. Here I think you are falling into the common interviewer trap of judging people negatively for not being exactly like you.