How Equal Temperament Ruined Harmony (and Why You Should Care), by Ross W. Duffin, is a cranky but fascinating look at how music went astray:
For nearly a century, equal temperament–the practice of dividing an
octave into twelve equally proportioned half-steps–has held a virtual
monopoly on the way in which instruments are tuned and played. In his
new book, Duffin explains how we came to rely exclusively on equal
temperament by charting the fascinating evolution of tuning through the
ages. Along the way, he challenges the widely held belief that equal
temperament is a perfect, "naturally selected" musical system, and
proposes a radical reevaluation of how we play and hear music.
You can get Bach’s Well-Tempered Klavier played this way, but to my ears it is not a revelation. Of course unequal temperament (not my preferred terminology) has struck back through popular music, whether it be bent blues notes, pedal steel guitar, and the drone tunings of My Bloody Valentine or Sonic Youth. Oddly the author doesn’t mention this. Listeners want variety, and simply "pegging the scale" does not control the real sound which results, just as in um…macroeconomics.