As a purist I abhor the idea of ballast being used to balance the car's behavior. Either design it balanced or suffer with the ill effects of a poor design. No more of this fudging with artificial balancing using weights. And then there is the principle of driver weight inequality.
I would like to propose an idea concerning the minimum weight rule for the cars. I think they should take a weight of the heaviest driver, say 75 Kg for Kubica, and stipulate that all drivers under that weight should have to carry a ballast of the difference between their body weight and that of the heaviest driver (say 75 Kg - 60 Kg = 15 Kg ballast for Nick Heidfeld while 75 Kg - 68 Kg = 7 Kg ballast for Lewis Hamilton). Furthermore the placement of that ballast must be securely placed in two locations immediately to the right and left of the driver's lowest rib shaped like a thin steak thus approximating the same CG location for all drivers and negating any advantage of placing the ballast "optimally". Then let the engineers design their cars to be balanced and as light as they can while still meeting the safety load and crash specs. This way you have a pure engineering challenge and an equality of the human element for drivers. Plus there is no unhealthy motivation for the drivers be dangerously underweight physically as is the current trend.
Personally I find it an abomination for a car to be carrying 70+ Kg of ballast as is the current state of affairs. Balance the cars by design, make them light as you can, equalize the driver's weights and go racing.
This seems so obviously fair and equitable that I wouldn't be surprised that it hasn't been proposed before. Any thoughts?