hahaha. to ski technically correct you need poles, its all about momentum of your upper body. hard to explain over the internet.
anyways,
at work, the level 3s always make the other instructors ski with out poles, they call them crutches...anyways, it is really good for your skiing good for your balance and focusing on steering and turning with your feet.
but when you get into the bumps, steeps, or any technical shit you need the poles
and even when ripping groomers, your poles continues momentum of your upper body
and on top of that, without poles, your timing gets all sloppy