Ok I apologize and stand corrected for some points.
But you said for international style tango it derives from wanting to express staccato, stillness, and curves. Why exactly those traits/movements if not to achieve a certain look for shows/competitions?
Staccato action is part of the basic character because the selection of music for International Tango almost always has a marching beat with strong note articulation. It is not nearly as varied as the music played at the milonga, because, in Ballroom, variety is expressed with an entirely different dance, not shades and flavors of a single one. Having said that, if a "non-standard" piece is played, an excellent Tango dancer will abandon most of the staccato action and use a character sometimes called "serpentine." No staccato in that flavor. But you generally only see a challenge like that posed to professionals or the very highest level amateurs.
The desire to have walking actions be curved comes from the fact that Tango, uniquely in the Standard discipline, does not use the technical action known as "swing and sway".
Swing and sway is critical to the task of moving two bodies freely in a straight line while squashed together in an offset position. Without it, the action loses its free and effortless character, with one of the following results: it becomes muscular and forced, uncontrolled and hectic, or tiny and devoid of all energy.
Allowing "walking straight" to gently curve solves all of the above issues. But why the workaround? Why not just use swing and sway to make it easier, just as in the other four dances?
Because Tango music, as played in competition, never asks for such an action. And music informs movement, not vice versa.
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Ballroom evolutions are almost never a question of "wanting to look cool and different." They arise when someone discovers that their current tools and tactics are not sufficient to let them express what the music makes them feel. So they adjust their tools, which adjusts their look.
When that expression resonates with others, they themselves adopt the tools that allow it, or develop their own approach to the same end. When a critical mass of people make such change, it becomes the new normal. And so on forever.
It is certainly not the substanceless, superficial posturing you might think it is. Ballroomers just aren't that boldly innovative--they by and large want to do "the same thing as that guy, but cleaner and better and more personally mine" than creating something truly novel.