I'll chime in as being solidly in agreement here. I can see where some people need the structure and routine, but CT nailed it - purpose and structure are different. Some days my purpose is to just enjoy life as it comes, while other days I have something that I need to do that brings structure in the form of a deadline or schedule.
In the working world you need structure because people don't always share the same purpose at work. There, structure gives people a purpose, just not the one they would have necessarily chosen.
But when I'm on my time and pursuing the things I think are important, structure comes when and if it's needed. And since it's mostly all my time now, structure is whatever I think is needed today.
Even more irritating than the "what do you do all day" question, is the comment "You're too young to do nothing" that I hear just as often. I may borrow someone else's line and start telling them I'm the manager of a closely held investment firm.