If any of the counterarguments to this were true you wouldn't see prices significantly lower on higher pop worlds but as someone with a main on Zalera who transferred from Balmung I can say things were infinately cheaper on Balmung. There were exponentially more crafters and gatherers selling. Even my current Cactuar alt can shop much easier than my main because Cactuar trumps Zalera in size.

Getting people more invested in selling on the market board will drive down prices because of simple supply and demand. More potential suppliers (whether they're the "old money" players who were at gilcap and dropped 750m on a mount or comparatively newer players who want those high-end glam items) means lower prices all around.

So much for that "higher understanding of the econony".