With a newfound techno-dance sound and deeper subject matter that’s representative of his turning point in maturity, born-again bad boy Justin Bieber’s fourth studio album “Purpose” delivers a pop star apology worth hearing. From his sentimental crooning in the first track, “Mark My Words,” to the R&B influences of the last, the once-troubled Canadian singer...

Oh boy! What’s it say about the state of music when Justin Bieber is living the most rock ‘n’ roll lifestyle of anyone creating music today? First...