Stephen Sondheim died Nov. 26, age 91, taking with him the last link we had to the songwriters of American musical theater’s golden era. A protégé of Oscar Hammerstein II, collaborator as lyricist with Leonard Bernstein (“West Side Story”), Jule Styne (“Gypsy”), and Richard Rodgers (“Do I Hear a Waltz?”), Sondheim went on to write both music and lyrics for a series of musicals that, as almost every tribute to him has said, “revolutionized” the form. I disagree. Sondheim did not revolutionize the musical so much as adapt it to contemporary tastes. That is not to minimalize his accomplishment, but rather to refocus it. In his great scores of the 1970s—“Company” (1970), “Follies” (1971), “A Little Night Music” (1973), “Pacific Overtures” (1976), and “Sweeney Todd” (1979”)—Sondheim changed the traditional, expected sound of musical theater songs in a way that made it impossible to write songs in the mold of Rodgers …