As Stephen Sondheim is the first to point out, it's the book writers of musicals who always get it in the neck. If they're not ignored entirely (as in "Sondheim's 'Sweeney Todd'" ), then they're usually held responsible for the work's shortcomings by critics, who tend to be more comfortable criticizing the story than the score.
SOURCE: Los Angeles Times at 05:37PM on May 6, 2011