"Fred Astaire" by Joseph Epstein (Yale University Press, 224 pages, $22) A decade ago, journalist Pete Hamill published a book called "Why Sinatra Matters." The same rehabilatory impulse motivates Joseph Epstein's "Fred Astaire," and the same underlying anxiety: Can this archaic cultural figure -- in this case, a skinny, jug-eared fellow who danced very gracefully in old movies -- have meaning for 21st-century audiences, now more accustomed to the flashy routines of "Dancing With the Stars"?