It should be no surprise that hip movement is one of the most, if not the most, important aspect of Jiu-Jitsu. There's a reason we do so many warm-up drills that involve hip movement. When you allow your hips to move, you gain mobility and leverage. If you're trying to power through something with a lot of strength, your body will be tense and tend to lock up. You'll lose the mobility in your hips that is such a crucial factor in so many moves.
I was teaching some half guard sweeps last night where you set your opponent down on their butt, and then come up into side control, passing their half guard as you come up. Some of the students were trying to lead with their head, but the correct technique involved leading with the hips.
This is definitely one area that separates good Jiu-Jitsu practitioners from the rest. If you haven't noticed, try watching them and see how well they use their hips to do everything from pass the guard, perform sweeps, control or submit their opponent, and much more. When you really start thinking consciously about how you use your hips, I'm sure it will start to open many doors for you.