I've realised why I never touched the expansion missions. I never got to rank 6. By the time I was level 50, it was difficult to find the people to form a level 50 party with to do that fight, as most had long ago done it.
This Trust Magic seems designed to help with that. I've blasted through a lot of the Rhapsodies of Vana'diel missions, and unlocked 2 of the trust things in each nation.
Soon I think I'll be able to do it on my tod, and get through to content people are still playing.
Fun so far. More time nonsense. It's the final part to the story, so perhaps worth coming back if you'd done all the other missions just to see it to the end.
Possibly, mine is. Try logging in here and clicking on the Final Fantasy XI bit. If you then click on Options List, this should take you to your characters and expansions.