@Moon What should it be? What do you imagine it will be doing?
i don't think separating data and style are wrong, but the purpose was never properly achieved. The idea was to make the web somewhat easily machine / device readable independent of style (consider Reader Mode in FF, or a braille reader.)
This didn't really end up coming to pass because most people building the web either don't care, but also, the web isn't "documents" as much as varying types of applications and "content" in DBs.