It allows the cyclist to do a 360 degrees turn of the handlebar during high jumps. You can see how a gyro brake system looks like up close in this video.
Don't like dirtying your hands with grease while removing rear wheel of your bicycle? Don't touch the derailleur cage and chain then. If you just called me stupid, it is obvious that you have not heard about Leonard Ashman's bicycle quick release system, "Hubdock".
Something to look forward to as it is not in the market yet.