Maybe because a person actually enjoys the crafting game in-and-of-itself? I would very happily create gear (and have) for people, making only 5k profit. The problem is that (a) I have only 20 bazaar slots on my retainers (b) very limited inventory space (c) low rank gear doesn't sell very well.
The problem YOU are bringing up could be solved more easily by fixing the "item seek" feature. If I could go look up buy orders for gear, I'd happily make things for people. That said, people who want to buy an item for 10k, while simultaneously trying to sell their moko grass for 5k a piece, may need to get a better grasp of economics.