Hingis has some of the best feel ever on the backhand side - that much is true. Her length, timing, accuracy and connection from that side is tremendous.
But there are many players who do far more damage with their backhands. Venus, Serena, Davenport, Clijsters, Sharapova and arguably Henin are but a few who spring to mind. And that's only from today's players.
Ultimately every player requires their backhand shot to be a weapon in today's game. Judged as a weapon, Hingis' backhand is some way down the list.