EVA cushioned outsoles are a great fit for exactly that type of riding. They use a lightweight foam midsole with rubber patches at key contact points, which keeps the boot lighter than a full lugged rubber sole while still giving you decent grip on snow and in your bindings.
The big advantage for park and all-mountain riders is dampening. When you're coming off jumps or landing flat, the EVA foam absorbs impact better than a stiffer sole, saving your feet and knees from jarring landings. You also get a slightly more responsive board feel compared to bulky lugged outsoles.
The trade-off is traction. If you find yourself hiking steep boot packs or traversing icy ridges, EVA soles won't grip like lugged rubber or Vibram options. But for lift-served resort days with occasional park laps, they strike a nice balance between comfort, weight, and cushioning.