Most games i play, there is a small pittance dropped from nearly every animal/beast/humanoid/monster thingy. So what, a few "gil" (in FFXIV terms) per mob is STILL better then 1 or 2 gil a DUNGEON I don't understand how this would be a negative thing. Sure there are a few zones (CM to name one) where gil dropping enemies may not be a good idea because of the ease of farming. But make it small, hell even 2-10 gil a kill is better then 0!
Perhaps give MOBS a chance to drop Allagan pieces that are level appropriate instead. The vendor trash item is already in the game, they should USE it!