I think YOU need to learn to ski.
Believe it or not, biesenthal is right. If you ever been in any kind of ski lessons and paid any attention, you would know that you would be turning wrong if you are using ur upper body to inisiate a turn. The only part of your upper body that should be moving is your wrists and arms when your pole planting and only so slightly. If you are turning with your sholders, then your not turning properly. Also resulting in setting your center of ballance off, and if your skiing anything too technical, you'll probably fall over. You already mention some well known mogul skiers, and im sure if you ask them, they would tell you as well that your upper body has to be completely silent or close too. They would also tell you that good technique is about edging, and actually inititating the turn with your hips.
And she's also right in the fact that park skiing goes against those fundimentals, because it actually relies on the seperation of lower and upper body and how they work together. So ya, park skiing and just normal skiing are different because of those aspects.
My advice, take a ski lesson, because its quite clear that you dont know what you are talking about