With no currency and no ability to trade items amongst other players it would be a very different game.

pros:
Everyone would have to hunt their own items to level their own crafting jobs to meld their own materia for their own relic quest.
No would would buy carries and there would be no RMT
Houses could be made through crafting instead of payed for.
Some things would take longer to accomplish keeping people subbed longer, and giving them a sense of achievement that simply doesn't exist when you just buy it, everyone wins.

cons: ???