Logical Disconnect: Why would gathering and hauling large sacks of coins make you better at casting dancing lights or improve your standing with Thor? Why would having a huge stash of priceless tapestries and gawdy jewelry increase your combat endurance? By this standard, porters and antique dealers should be pretty badass.
GPs are not inherently commensurate with the difficulty of acquiring them: A million GPs guarded by a hoard of syphilitic stirges, 16 flatulent purple worms, a commune of aggro-liches, and a venerable arch-demodragon are worth just as many XPs as a million GPs guarded by a single leprechaun sleeping off a 3-day bender. You can make up some sort of bylaws to assure that the value of treasure retrieved is correlated to the difficulty of acquiring said treasure, but any work-around you come up with is as good as a sworn admission that XPs for GPs is deeply flawed.
|How much for the sack?|