Not true, you don't have to drop your hands to torque your hips, there's no correlation between the two. It's just a habit that most get into, I used to do it myself. Practice going through the motions of the kick slowly getting the hip rotation with the hands up. You have to recognize and acknowledge that you're doing it before you can correct it. Take the ATT video for example, the coach walked him through the concept slowly at first and as soon as the kid started getting it he got over excited with the new found power and started throwing kick after kick quickly abandoning a lot of the technique. One of my coaches used to drill into me, "Slow and accurate make you good and precise, fast and sloppy make you fast and sloppy". Spend some time here and there walking through your techniques (shadow boxing) in front of a mirror slowly making sure everything is where it should be. One benefit from slowing down is you'll start to understand body mechanics better.