I don't have time for another sketch - but the center of lift does not move on the rudder (not significantly anyway) with the angle that it flows through the water. This is why raking the entire rudder system forward or back does not affect the helm. When you rake the rudder in relation to the pivot axis, then it affects the helm because you are moving the center of effort of the rudder in relation to the pivot.

However, the efficiency of the rudder (or wing) is greatly affected when you move the whole thing forward or rearward. For example, visualize the difference in the straight(ish) wing of an aeronautical heavy lift cargo plane and the swept back angle of a fighter jet's wing. If the rudder shape / draft line, is perpendicular to the water flow, the water flows around the foil as the foil was drawn / designed. If you angle the rudder forward or rearward in relation to the water flow, this has the effect of stretching out the designed foil shape. I can only imagine that the likes of Robbie change the angle of the gudgeon's to keep the foil shape flowing through the water at it's designed angle or to perhaps slightly elongate the foil profile....some pretty dramatic changes happened to the Tornado (I assume you have a boat that was built pre-spinnaker). Perhaps they found that those foils work better at a more swept angle (sweeping forward or rearward has a similar affect).