The musical world suffered no great loss when Will Smith ditched rapping for acting. His ’80s hip-hop, as the Fresh Prince, had marginal novelty teen appeal. But his first album in four years is worse, lapsing into nonstop pop-rap clichés. Even the smash single “Men in Black,” included here, merely exploits his celebrity and the goodwill built up by the movie. At this point, Smith has as much business rapping as Eddie Murphy does singing.