The whole subject of "rotary skills" is fraught, because it embraces several very different types of movement. Simply allowing the skis to make a brushed or skidded turn can be called a rotary skill, although it's really a
result of a combination of body movements. The ability to control the turning of the femurs in the hip sockets can be called a rotary skill, although that turning usually results only indirectly in the turning of the skis, usually through that femur rotation promoting edging. Control of turning the feet solely via the lower legs and subtalar joints can be called a rotary skill. That may result in a pivoting of the skis, or have a different effect, depending on the situation.
All of which demonstrates that while we may be of the view that PSIA has overemphasized rotary skills, no one skill can be viewed in isolation. They're all intertwined, and none should be neglected.
Exaggerated edge angles from an oversized wedge will only happen if the instructor allows it. I agree, you can't go there.
So...there's a case of the skier needing to refine control of the turning of the femurs, so as to be able to adjust the wedge size and degree of edging in that wedge as desired.
This brings up the "Other Balance" that maybe needs more attention at the beginner level and that is "Lateral Balance"
Lateral Balance and edge angles are closely tied through both inclination and angulation. This is where the wedge can become problematic in that the spreading of the legs inclines the COM (in 2 directions) relative to the femurs and as the turn develops added inclination (leaning up hill) in defense of Gravity only makes matters worse.
So angulation now needs to be a teaching focus, allowing the joints of the foot and leg to be the dominant driver of increased and decreased edge angle.
If I understand you correctly, we're speaking here principally of "knee angulation" created through foot tipping. The need to start developing rudimentary angulation skills arises as soon as the student starts arcing wedge turns farther across the fall line on a slightly steeper slope. If the student remains stiffly in the initial wedge posture, he'll tip outward and start to "highside." One instinctive reaction to that may be to relax the edge angle of the outside ski so as to let it slip outward and reduce centripetal force. The skier then fails in the quest to "complete" the turn. Instead, the skier needs to maintain the bit of angulation of the outside leg that should be a natural consequence of correctly creating the wedge, while shortening the inside leg so that the center of mass can be inclined inward by the amount necessary to maintain balance against centripetal force and the force of gravity.
I will submit that building edge angles via angulation is easier that releasing them and since the wedge presets edge angle it is important that angulation be the focus vs just separating the legs.
...IMO, this is where we introduce the advanced skiing concept of Outside Leg Relaxation OLR. There is no reason beginners can't embrace this concept at a rudimentary level.
Well...I don't think that those of us who have been skiing a while find it
physically difficult. It's mostly just a relaxation move, after all. But it's definitely
mentally difficult for many new skiers. They need to wrap their head around the idea of giving up balance, giving up
perceived control, and letting themselves accelerate down the mountain, without, it first seems to new skiers, any brakes. They need to discover that the new outside ski actually will catch up to them and give them a new point of balance--every time. It's good to first learn this on a
very gentle slope, because then the "catching up" happens quickly. It takes a little longer as the slope gets steeper.
But yep, before you can release, you need to have something to release
from, and that means angulation adequate to maintain grip.
And all of this
can be done in a wedge.
Agreed locked edges via a wide wedge is out. However, the implementation of angulation at low speeds should provide for a full, manageable range of edge angle so having a mini progression to teach this set of movements is probably a good idea.
And then...as the skier becomes more confident, the skier can be encouraged to make the wedge smaller and smaller. (Or it may happen spontaneously!) The need for the outrigger diminishes. The skier discovers that the inside ski really isn't doing much. The skier discovers that having that large pre-set steering angle at the transition isn't necessary. The skier finds that as the slope gets steeper, that inside ski in wedge orientation really starts getting in the way in the last phase of the turn, just wants to push him off the hill.
Agree, we are all looking to shape the turn, but centripetal force does not exist unless the ski creates it. As I have stated multiple times, it is a matter of intentional vs unintentional resultants. It is difficult for someone to control a force inadvertently generated because of a desire to redirect the skis vs managing a process that actually creates a turn.
And what's necessary for the ski to create centripetal force? Edge angle.
Full circle.