I only play the US Normandy campaign as I try to max this team, and am at 80 hours of gameplay so far. In this time, I have only been apart of two successful matches of assault. As we all know, the game mode has both teams rotating points between owning just A but not B, or owning B but not A. Then both teams try to cap the other point and in doing so, we just trade points. This results in the US getting stuck at endlessly capping A and B because the Germans can recap just as fast as the Americans.
My suggestion is to increase the time it takes Germans to recap a point for every time they successfully take the point back. For example, If the US took A, it should take the Germans 10% longer than normal to retake the point. If the Americans retake A, it should take the Germans 20% longer to take A again. This continues until it takes literally twice as long for the Germans to recap a point.
This should definitely allow the Americans to get to the rest of the map more often. (If this is any issue across all campaigns, then it will help the attacking team in general)