Hmm--interesting thoughts here, Roto, but I'm not quite clear on the question. Are you asking about wedge vs, parallel, about simultaneous vs. sequential movements, or about offensive vs. defensive movements? They are not the same questions--wedge and parallel both can involve either simultaneous or sequential movements, and both can be offensive or defensive.
I'll agree with the others that there are no bad movements--but there are certainly bad habits! As in a car, braking is an essential skill to master, and an important part of the skillful driver's and skier's repertoire, but riding the brakes is a bad habit.
Offensive wedge turns and wedge christies, just exactly like offensive parallel turns, involve simultaneous (for all practical purposes) movements. They all answer the offensive "GO" intent that Todo refers to--they're all attempts to "go that way," not to "stop going this way." They're attempts to control line, not speed, to go precisely where you want to go, as efficiently, smoothly, and fast as possible. They are not brakes! They all involve simultaneously turning both ski tips in the direction you want to go, with no pushing/twisting of the tails in the opposite direction.
They are quite different from braking snowplows, STEM christies, defensive hop turns, and hockey stops, all of which involve twisting the tails out into a braking skid. Stem christies are sequential--first the uphill/outside ski stems out, then the inside ski is moved out toward the stemmed outside ski to bring the skis parallel. Hockey stops and hop turns are simultaneous movements (again, for all practical purposes).
I say "for all practical purposes," because none really, truly involve precisely simultaneous movements. In my opinion, the disctinction between simultaneous and sequential is overrated, and misses a more critical point. What really matters is not whether one ski turns before the other, or how much time lag (if any) there is between the movements. Far more important is which ski turns first?
In offensive "go that way" turns, the inside ski turns first--in the direction of the turn. It has to--otherwise it's in the way of the outside ski, which then can only turn tail out into a skid. The outside ski can follow immediately--virtually simultaneously--or not. It really makes little difference in the outcome of the turn, or the fundamental character of the movements. "Right tip right to go right, left tip left to go left" is the key triggering thought for all offensive turns, wedge or parallel, steered or carved.
In defensive braking movements, the outside ski turns first. Again, it has to, because it has to get out of the way of the inside ski. Again, they can be virtually simultaneous, as in hockey stops and hop turns, or clearly sequential, as in stem christies or converging step turns.
It's important to understand that "simultaneous" does not necessarily imply "equivalent." In a wedge christie, for example, both ski tips steer into the turn, but for various reasons, the outside ski tends to turn more quickly, causing the wedge. It is difficult at very low speeds, especially on steeper terrain, to roll the downhill ski completely off its uphill edge, and as we've much discussed, any active move to lighten or lift that ski BEFORE initiating the turn involves an unproductive "negative movement" uphill. So it is harder to turn the downhill ski at the start of the turn (at low speeds), resulting in the likelihood of the skis opening into a wedge, even as the skier tries to steer them both simultaneously. As the turn progresses, the pressure on the inside ski diminishes, the body moves farther inside for balance, and the inside ski rolls to its outside "little toe" edge--all combining to make that inside ski easier to steer than the outside ski. At this point, the continued effort to steer the "right tip right" causes the skis to "match" (become parallel), as the inside ski turns now more easily and quickly than the outside ski.
So the rates of the turning movements of the skis vary (unintentionally, but nearly inevitably) in wedge christies. But the timing and intent is still simultaneous, as both turn at (virtually) the same time.
So the sequential movements that cause problems (in offensive turns) are those in which the outside ski twists first, tails out, before the inside ski releases, causing a negative (away from the turn) movement, and a braking skid. Sequential movements--as exaggerated by the "thousand steps" exercise--in which the inside ski turns its tip into the turn first, followed by the outside ski tip turning into the turn, are still highly offensive.