I was struck by the relevance to this discussion of the following
quotation, by George Pratt writing on J. S. Bach in the BBC MAGAZINE:

   Bach wrote within a well-defined lingua franca.  Before Romantic
   ideals required composers to become highly personal and distinctive,
   the fundamentals of musical composition ... were common ground.  Bach
   had a masterly grasp of this universal language, and of its various
   national dialects. ... {His} composing fluency is less analogous to
   the intensely personal languages of Stockhausen, Reich or Boulez
   today than, say, to that of composers of musicals, despite their
   wholly different aims and function.

Dorothy Smith