In racing, everything is driven towards maximizing the tire contact patch and giving it as much traction as possible. Aerodynamic devices add downforce with little added mass. So logically, more downforce = more grip. And the early attempts dealt with it directly, vector the downforce directly to the tires by connecting the wings to the suspension uprights.
The benefits are that the chassis and it's required suspension geometry and action are isolated from the downforce. Because (as in the present system) with a wing pushing down on the body and the body pushing down on the suspension, tuning the suspension becomes very complicated and the chassis rides very harshly. The benefits of attaching the wings directly to the suspension uprights is that the chassis can be tuned just for mechanical grip without being concerned about aero loads on the suspension. Additionally, the ride in this system is less harsh, giving the driver and all chassis components a smoother and less harsh ride. The downside is that any bumps in the track surface are transferred directly to the wing struts and wings, leading to the increased possibility of failure.
In the photos below the Chaparral 2J has a rear wing attached directly to the suspension uprights.