Certain things are unchangeable. The soles of our feet, and bits of the sides of our feet, are our connection with terra firma. All the forces mediating between our bodies and the outside world ordinarily go through there. All the feedback we get with our sense of touch comes through there. If it's coming from higher in the body, it means something has gone terribly wrong! Stiff ski boots will give us some feedback through the shins, but our sense of touch there is poorly developed, and the feedback will be crude. Look at all those little ridges on your foot soles. They're there to serve a purpose.
I don't have the background to fully understand how the "kinetic chain" gets fired up. I'll leave it to others to describe that. You can find much that's been written in that subject.
But I can say this. I believe in embracing and building upon the natural functioning of our bodies. Trying to develop skiing movements that run counter to that isn't likely to work out well. By initiating skiing movements with the feet, we harness and build upon the evolved natural abilities of the feet to bear forces in ways that function best, allowing the feet to pass those forces up through the skeleton and musculature into the upper body. This promotes balance, or deliberate imbalance when and where called for. This immediately places the sensitive parts of our feet in strong, functional contact with the forces coming up from the snow, allowing the nervous system to receive the full spectrum of information needed for us to make rapid conscious and subconscious decisions going forward.
To propel us across terra firma, the feet are evolved to change shape or deform a bit through the cycle of our stride. The same remains true when we are sliding over terra not-so-firma. Think about a steel arch bridge. The steel has some elasticity, so when a great weight is placed over the arch it deforms downward a bit, and redirects and redistributes the downward force toward both ends of the arch. Feet function in a similar fashion.
Why would we want to impede that natural functioning? I find very credible and persuasive the arguments of those who advocate soft footbeds that don't place stiff support under the arches. Even they acknowledge that individuals differ, and that there are some persons who due to individual anatomy, or anatomical changes over time, need extra arch support in order to withstand the heightened forces that dynamic skiing produces. But for most, the goal should be to complement the natural functioning of the feet. The underside of the main arch of the foot is not evolved to be in weight-bearing contact with the ground!
The high, stiff cuffs of ski boots do serve a function. Ordinarily, the forces generated in a ski turn should continue to be borne through the feet. However, skiing can generate forces that are stronger than ordinarily encountered in walking or running. Thus I would say that contact between the shins and cuffs can productively bear some fraction of the peak lateral and forward forces a skier experiences. It just shouldn't become a substitute for more natural processes. (Maybe most importantly, those stiff cuffs help us catch ourselves and recenter when we encounter rough spots or something unexpected happens.)
The available range of tipping of the foot inside a stiff ski boot is obviously small. Creating substantial ski edge angles also requires inclination and the involvement of all the joints up the chain. However, starting with those relatively small movements inside the boots is crucial in order to place the correct parts of the feet in functional contact with the boots and, indirectly, the bindings, skis, and snow.
Natural movements should result in comfort! I don't know about you, but my brain prefers to restrain me from doing things that are uncomfortable, so comfort is going to improve my control!