As a current J user, no, I don't see the need for a 'third pair of eyes'. The aircraft was designed for 2 pilot operation, there simply is not enough to do to require a WSOp (or are we really talking about WSOs here?) The Italians carry a third pilot, having spoken to them they said he read the FRCs & did the radios etc, but were a bit vague as to what the PNF did!
If we're talking about actually investing some real money in the J rather than throwing it all at the K, fitting JTIDs etc, then possibly we might need the WSOp(ALM) to put the teapot down & multi-task even more than they already do! This discussion should be about the best way to operate the J, not finding jobs for under employed K WSOs.