“[T]hough he’s an influence on today’s new-folk movement, young musicians and fans haven’t embraced the 69-year-old Mr. Simon with the same gusto as his few peers. Songs by Mr. Simon aren’t covered as often as those by [Leonard] Cohen and [Bob] Dylan and [Joni] Mitchell, and there’s been no cross-generational celebration of his work” comparable to Todd Haynes’s Dylan film I’m Not There.