It really seems like you don't understand how Sass works, or at least haven't actually run it. If anything, Sass layers more gracefully than C does over x86, since compiler-generated x86 is incomprehensible, and Sass-generated CSS is probably more readable than what a typical designer produces. Sass also promotes CSS best practices, in part by automating them, and in part by providing syntactic sugar for them.

If your designers can't grok Sass, you do what every professional team using template languages has always done; you back-and-forth with the designer in CSS/HTML, and you convert final comps to templates. Designers by and large don't speak Haml, Erb, Clearsilver, or Cheetarah (or Mum-raah or whatever Django calls it) either.