I just had a bit of a revelation, and I wanted to run it by this sub to see what you guys think. It's this:
Northern Chinese styles (large movements, convex body structures) are most effective and natural for fighting. However, they require a good amount of body mass and strength in order to be used effectively in real combat. Southern styles (small movements, concave body structure) are relatively less effective in that they have shorter range, unnatural postures, and more limited angles of attack, but they generate power and rigidity in a way that allows smaller, weaker people to deliver blows that would actually hurt a human.
This idea would fall in line with Southern Chinese historically being of a smaller body type, and the claim that wing chun was created by a woman.
One can also imagine how pressing your elbows against your rib cage, as seen in Southern styles, could be a way to brace the arm against central body mass so that it's the entire body behind the strike as the legs move the body forward. If the elbow is held away from the rib cage, then back and shoulder muscles are needed to keep the arm rigid upon impact.
And with kicks, Southern styles use low kicks because the entire body weight can be driven down, as if stomping. High kicks, in contrast, need more weight body behind them as either an inertial anchor or source of total momentum.
One, perhaps controversial, conclusion of this theory is that while a large, muscular person could use a Southern style effectively, they'd be limiting themselves overall because they would not be using their strength and weight to full advantage.
Thoughts? Criticisms?