Put a vendor in major cities that sells dungeon gear for, say, Poetics, since everyone always seems to have so many. But you have to have the exploration achievement for a given instance to buy gear from that instance, and nothing in the current Expert roulette, to keep people running them. Maybe leave out the most recent set of Alliance raids, too (not specifically the YoRHa raids, just whichever is the current level cap of the expansion), for the same reasons.