Rather than a folding wing, why not a partial swing-wing, say one that swings at approx 2/3 of the way out? Fully forward for landing, swung partly back for cruise, all the way back at the gate? I know it would mean extra weight, though.
For the same reason that only one carrier aircraft used swing-wing oversweep to reduce aircraft shadow on the ground and all the rest used folding wings. It's very complex and adds lots of weight and cost. The swingwing oversweep only made sense because the Tomcat already had swing wings for entirely other reasons.