Efficient Arm Profile:
A large flat surface under your propellers wastes thrust. According to Isaac Newton, every action has an equal and opposite reaction. In the case of drone arms, the thrust generated above them is equal and opposite to the air pressure exerted on the arms; they cancel each other out. You can think of it as the flat arms blocking the thrust that is created directly above them. Whichever way you think about it, allowing the air to pass through the arms saves the thrust and battery power you would have wasted by blowing air against the quad's arms.
Designed for Airflow:
Air intakes deliver cool air from the outside to parts that would otherwise have a problem with heat when placed in an enclosed canopy, specifically the VTX and ESCs.
Vibration Isolating Motor Mounts:
Flexible polyurethane motor mounts are popular now because they dampen gyro noise which allows for a more aggressive PID setting. Typically a flat piece of polyurethane is placed between the motors and carbon fiber arms. That helps a little, but vibrations can still pass through the motor screws, to the back side of the arms and from there to the rest of the craft. Even if you had polyurethane on both sides of the arm, the screws still come into direct contact with the inside of the holes drilled through the arm. These motor mounts are better and totally unique. The motor and the motor's screws never come into contact with anything but polyurethane. Small bumpers on the ends of these mounts protect the carbon fiber arms from landing on concrete or other hard surfaces which can eventually make carbon fiber delaminate.
A flat piece of carbon fiber angled into the wind at a 45 degree angle is almost the least aerodynamic thing possible. The angle generates downforce (the opposite of lift) which your motors must struggle to overcome, and the exposed electronics create turbulence which adds drag. Essentially, the average multirotor frame made today is even less aerodynamic than a gardening shed. The Osho 210's canopy reduces drag with its gentle curve and reduces downforce with its sloped back while enclosing and protecting the internal parts that would only generate turbulence as they cut through the air.