First, solid wings are dramatically better in lift drag ratio.
They start out around 3x better per square meter than conventional sails on a bermuda rig, and can get up to 7x better with careful design. This is why the America's Cup boats with wings are dramatically faster than conventional rigs (the other reason being foils).
Second, the simplicity of the rig.
These designs are self trimming, which means there's a control flap you set, and that causes the wing to have a consistent angle of attack vs the wind. As the wind vector shifts around the sail just tracks it without needing any active control or electronics. You only have to change the control flap when the bow or stern crosses the wind during a turn.
If you get into severe weather you just put the control flap in neutral and the wing just acts like a weather vane. Surprisingly enough a feathered wing like this has less drag than a bare cylindrical mast with no sail lifted. Aerodynamics can be counterintuitive.
That's what's so cool about this technology. It really is just a bolt on.