I don't think that picture illustrates your point well. It seems obvious to me that the kid is doing a wheelie or some such thing for the camera. Also, if you ski a lot, riding with different stances will help you find your center and ski better.
I teach ski lessons and I have my skiers straightline, ride in the backseat, ride in the front seat, try to do wormturns, sideslip, pop and do 180s on the snow, ride their edges to an absurd extent; anything I can think of that will get the person to use their skis or move their body in a different way. These exercises help the learner find their center of mass, and will lead to them skiing more efficiently as they realize what movements work and which ones don't on their skis.Most importantly, it's a lot more fun for the learning skier and will make them want to come back.
Being mobile on skis is very important because every situation requires a different set of movements and different body position, which changes instantaneously. Trying to make the same turn on any terrain just doesn't make sense to me, but if that's your thing, go for it.
