Yeah, I was disappointed - if admittedly not entirely surprised - that the route was one-time only. I guess while that particular destination could fairly easily have been balanced with the Tramp Steamer for cost (in echoes/actions) it would leave the question of why you can’t get to all the other islands via Parabola, and arranging/balancing the whole lot would get messy.
Still be a nice option to have, though! :)