One can generate tons of power without Sine-Wave or hip twist. If one can keep knees bent and smear feet to link body from ground through legs then core and finally through the striking arm it's very powerful. his type of punch depends on the back muscles to generate a devastating strike.
The key is to be mobile enough between strikes. When the opportunity to strike comes one must be grounded immediately to launch the punch.
This comes from a self-defense perspective. In a sport setting one might not get the opportunity because opponent is bouncing around.
Agreed. if you take K-1 or a Muay Thai Fight, you don't see the fighters bouncing around like they're on springs etc. they have solid stances and react instinctively. I prefer old school TaeKwonDo before the Sine Wave when they were more into martial arts than trying to create and Olympic sport or differenciate themsleves from Japanese Karate - Tang Soo Do MooDuk Kwan concidered by many as Korean Shotokan is a very very nice style and they don't use this "sine Wave". If the Sine Wave was actually useable surely a few other style would have adopted it?