It’s about much more than simple entertainment, they said. — -- “Ben-Hur,” the epic 1959 tale, is coming back to the big screen today, this time re-imagined for a new generation of moviegoers.

Of all the film genres, the epic is one of the hardest to define. Must it be a period piece? Must the plot center on a hero? Why is “East of Eden” (1955), with its relatively meager runtime of 117 ...