This is often why I push for storymode to NOT include Raids, or to have a solo mode of all content where you have npcs that fill out your party.
Easy:
Light Party
Option to bring a friend or 3. NPCs will fill the remaining slots.
Reward the current Tomes for non current gear. (Solidarity etc) Will chance of out of date gear to drop.
List it via Duty Finder:
Ex: The Coil of Bahamut Turn 1 (Story)
Crystal Tower (Story)
This way folks can bare minimum see the storyline without getting carried, paying for a clear, and "inconveniencing" players who have already cleared.
They can farm their glamour armor, and normal modes, hard modes, & etc remain untouched.
