In an enormously generous gesture to the American people, the Grateful Dead appear to be packing it in for good this summer after three concerts in Chicago. “These will be the last shows with the four of us together,” band member Bob Weir told Billboard earlier this month. In doing so, the Dead will bring down the curtain on 50 years of plodding, limp, turgid, languid, unoriginal, inanimate, self-indulgent stoner music, an embarrassing relic from a bygone era. One can only hope that James Taylor will soon follow suit.

The...