Cropped or waist-length jackets end at or above your waist, giving you maximum mobility and a street-inspired look. They're most popular in the park and freestyle scene, where freedom of movement matters and riders spend more time hitting features than sitting in deep snow.
The big trade-off is coverage. When you bend over to adjust your bindings or sit on a cold chairlift, your lower back and waist will be exposed. In deep powder, a cropped jacket won't keep snow out — even with a powder skirt. That's why this length is rare in dedicated snow jackets; most riders need more protection.
If you primarily lap the park in mild conditions and value mobility and style over full weather protection, a cropped jacket can work. For all-mountain riding, cold days, or any powder, you'll be much happier with regular or extended length.