wow fairly mellow terrain in amazing perfect snow. A beautiful video but almost anyone can ski hero snow with out poles. its soft, perfect, you're floating, it's amazing and dreamy but when you get to real more common condition such as slightly crusty deep crud and you're skiing much faster than the skier in that video, that is when poles come into play. i'm not saying they are 100% necessary but they certainly make it a shit load easier to stay centered. And who wants to make skiing harder for themselves? if I wanted to do that I would ski on straight skinny skis.
Also without poles you are very limited in your mobility, you cannot traverse half as fast without poles as you can with poles, and some narrow uphill traverses are damn close to impossible with out poles. Not to mention the B.C.. Go try a long tour without poles tell me how that goes.
FWIW. I broke my wrist last season and was forced to rock no poles all over the mountain for a good part of the season. So I know that it is definitely possible to ski w/ poles out of the park. It just sucks. if it is corn snow, groomers, or perfect pow i could see where people might start dropping their poles for fun but otherwise just seems like more work to me.