In deep powder, ski tips have the tendency to dive beneath the snow. Because of this, many skiers compensate by leaning backwards, which is the Number 1 no-no when it comes to skiing with good form (not to mention it rapidly increases the likelihood of a knee injury).
Rocker has changed all this. A rockered profile makes it far easier to keep your ski tips on top of the snow, and you’ll be less likely to dive forward if your tips get caught. This allows you to ski in a more aggressive stance—weight forward, hands in front— just like you would carving on a groomer.