An automatic winding system is inherently weak and during shock or extreme forces it can break. As a sort of "well we might as well include it" feature, Urwerk wanted to make the automatic winding system more interactive. Fully stopping the rotor will stop automatic winding, but will also feasibly protect the movement during certain sport activities. Reducing the efficiency of the spinning engages an additional gear (which is part of the "Turbine Control" system, and slows down the winding. This is useful if you are doing things like playing golf or other activities and want to slow the rotor to protect it. The rest of the time you can keep it on "full." It is easy to say that "well with such an expensive watch why would you wear it when it might break." I would agree. Not only that but the system requires you to plan in advance if you are going to take it into danger. Talk about an extremely horological lifestyle. In the end it is a sort of fun complication - that again - is meant to increase interactivity with your high-end luxury timepieces.
It can be interesting to know how much the time on your watch deviates from the true solar time, but it doesn't actually matter in terms of coordinating with the civilized world's schedule. It is a reminder that the way we measure time is celestially inspired, but that doesn't mean it can help us be on time or plan our days any better.
2. Moon Phase Indicator
The Great Gatsby is one the biggest movies showing in cinemas now. Starring Leonardo DiCaprio and Carrey Mulligan, it is a tale of love set in the Roaring Twenties. Coincidentally, the 1920s were also the time when wrist watches started to gain traction amongst men and women.