Forgive me, but I don't really think you DO understand. I don't want to be condescending (and if I do, sorry), but you are confused over what bonsai styles are, as well as how they are executed with trees to create credible bonsai.
The "S" curve stuff is aimed at beginners. No bonsaist really wants to be expert in creating those. They are not a "style" as much as they are unnatural looking junk. It's mass market, mass produced. No real talent involved. It's good you don't find them attractive, but you keep lumping every other style --except formal upright and broom) as being "curved" or "s" style--or so it appears to me.
"Traditional" bonsai styles are more natural looking and generally follow the manner in which trees actually grow. Also, styles have many variations and experts know how to tweak them to make more dramatic trees using those styles as starting points. Ultimately there are no 'rules' or mandatory styles, only the designer's ability to use those 'rules" and basic forms to create. But first, the designer has to understand how to make the basics...
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