Reasoning for different roation
A boxer is different than a WC fighter because the style or form or way he uses his body. A boxer bobs and weaves where as in wing chun traditionally there is no bob and weave. The boxers generation can also come from the bob or weave as they when they throw a hook or upper cut they slightly sink and then rotate or shift the weight. With Wing Chun you use your limbs to protect you and there fore your body is more balance and with less movement of head. The head is more static than in boxing where you move the head away. The hands are what you use to attack with. So there for the structure is different. When you use the hips and arms in unison it because there is no need to sink first to generate force. Now a boxers hook will be more powerful than WC punch any day. But the WC punch with rotation does not just give you extra power it gives you more range of motion. Which allows you to collaspe your opponents structure or add power to your strike. In other words you have a longer follow through depending on how close you are to your opponent.
But being able to turn and rotate with a punch is nothing unless you practice doing so first on a heavy bag and wall bag then implement it with sparring. How many of you have actually hit someone with that sorta of punch?
addtionally the rotation is not just for punching. Other hand techniques can be use with the rotation like Jut sau or Tan sau. To uproot or displace your opponents balance. Also you can use the rotation with lop sau to turn or shift your opponents attacking line so you can attack them from their blindspot!
The Flow is relentless like a raging ocean with crashing waves devasting anything in its path.
"Kick Like Thunder, Strike Like Lighting, Fist Hard as Stones."
"Wing Chun flows around overwhelming force and finds openings with its constant flow of forward energy."
"Always Attack, Be Aggressive always Attack first, Be Relentless. Continue with out ceasing. Flow Like Water, Move like the wind, Attack Like Fire. Consume and overwhelm your Adversary until he is No More"