Please excuse my ignorance, but what type of arrestor gear is available on our new carrier in the event of an F-35B's lift fan failure and the aircraft being forced to land conventionally?
If there's no diversion airfield available I should imagine it's a combination of a parachute stored in the pilot's seat, and a helicopter on board the carrier. Much like the Harrier...
Edit: I should imagine the economics are fairly straightforward. Multiply the number of aircraft you expect to lose from lift fan failure by the cost of each aircraft. If that number is less than the combined cost of installing and operating dedicated arrestor gear on the carriers, and of adding suitable hardware to each airframe, then it's not worth doing...