.... pointless carriage of spare engine, wasting the payload, for whole life of aircraft?
Looking at the NTSB statement I would suggest that this was a pointless loss of aircraft due to the inappropriate actions of a pilot. Thankfully with no loss of life.
As stated by SASless, the aircraft would have had plenty of power margin to safely complete a landing on the deck, assuming the approach profile was flown correctly.
So this is an event that
should have proven the benefits of two engines.