Bach had some complicated, almost math-like themes, but is it really more complex than Wagnerian leitmotifs and huge orchestral settings or Schoenbergian modern music where the traditional score notation can't keep up anymore?
But yeah, the analogy is easy to abuse, due to the multitude of artistic styles, and active rebellion against the "mainstream". For every Piet Mondrian out there, you can find a Chuck Close.
Perhaps the musical analogies just break down here, I'm not sure that they are helpful...