Or you can disreguard all that science and just say it is fun.
Rolling along on a trike is the most relaxing way to ride. You can ride at any speed or just stop for a while. No need to unclip. Besides that it is a great machine to ride to a location to view what ever you want to. You have your own lawn chair with you to comfortably sit and watch. Or----------you can ride it across the country without worrying about where to lean it.