Allagan Gold Pieces an easy solution to two problems! =D
Many people seem to find it not at all worthwhile to clear trash in high level dungeons, additionally, many people also seem to have serious gil issues once they hit end game.
Both problems could be solved at once by giving trash mobs in high level dungeons a reasonably good chance to drop Allagan Gold Pieces, perhaps have the mobs that drop one, do so for everyone in the party, to avoid it ending up where one person seems to get them all in some dungeon runs. The chance to drop would need to be carefully chosen of course so as not to add far too much gil to the economy.
Either way this would be a pretty easy way to solve 2 of the issues that seem to be generating the most complaints. Not that I'm complaining myself, but just thought I'd put this idea out there.