Rekindling life in a dead frame

Why re-write Frankenstein or The Modern Prometheus as The Casebook of Victor Frankenstein? The rewriting of well-known novels generally depends upon two techniques. The first involves recasting the narrator: telling the tale from a different point of view, usually that of the historical underdog (women, servants, woodworm, etc). The second is to update the novel, reinventing it in modern dress.