Increase the exp of the fodder wandering around. Add generic items like Allagan coins to the loot tables globally. Add random drops of level-appropriate aetheric gear. Add zone drops that are sellable, and are pieces of gear with vastly better stats than anything else of that equip level. Add other things specific to a given mob family and zone, like minions or having some ADS thingers in Azys Lla you can whack for exp that have a small chance to drop an ability glamour item(also marketable) that lets you turn MCH's turret into a node(figure if they're going to do it with with egis eventually, why not let the other jobs in on the fun?).

Put in a lot more out-of-the-way pockets of useful mobs, like ones that have higher drop rates for their family materials, or flying around under the islands in Churning Mists to locate a cave with a bunch of tightly-packed plasmoids for SBing. Even add flavor drops, like colibris and apkallus dropping varied fish of a matching level range. Add more ore types to coblyns, or even give them a small chance to drop tier I or II materia. There are so many things that can be done to make critters out in the world more interesting to beat to death.