My family and I, unfortunhtely, never had the opportunity to ride to Ferry when it was in service for a short period of time because of protest from the people of Kauai.  I was born on that island an I am not sure if that was Kauai's local born people wish or the mainland transplant that is growing on my island?
  But we were on a ferry ride (20 minutes) from Seattle Wash to a small island across from the main.  It was so smooth and just real enjoyable family ride.  Although this ferry carried cars, as we did, for that beautiful smooth ride.  I am not sure the Ferry to Kauai you could bring your car on the ferry.  
   I would hope they bring the ferry back not only for a ride to the island of Kauai but to Maui and the Big island of Hawaii.  Just imagine spending your day or weekend on another island with your own car.
    I am not sure if our local Hawaiian Airlines and rental car agencies would lobby against the ferry because it would take away their profit.  Just a thought.