Will you really go back? I suspect that 99.99% of players won't. It's more effective to go somewhere new, where you get XP, a fresh shot at better loot, and maybe different quests.
Sure, you can ruin the economy in many ways, such as hoovering up every bit of loot. It isn't balanced around that though, and can't be. It's the correct assumption almost always that players won't return for loot that was left, because it's less valuable than doing a new dungeon.