The high-end market for crafts can sustain only so many crafters regardless of server, all the Legacy servers moreso than another other servers have a glut of max level crafters. This causes prices on many items to fall well below what is available on less contested markets. I'm one of the few people I know with maxed crafts/gathering on Marlboro so I can make a pretty decent profit with little effort due to minimal competition in the high end market.
On Hyperion my old FC had to really hustle day in and day out just to afford a medium house and I could easily make that gil solo in a week on a non-Legacy server if I put my mind to it. High-pop servers have upsides and downsides, and since I'm not really interested in raiding it's all downside to me at this point.