A healthy and dynamic economy is one of the things I enjoy in MMOs that I cannot get in other games. So yeah, making almost no items sellable would be terrible. In addition, to accomplish that, you'd also need to disable trading of most items, so you couldn't even be nice to your friends if you wanted, because it could be "exploited by people wanting things in return", and it would also make the entire crafting system in the game almost entirely useless.