I agree, it "would be nice," but I also understand and respect why it isn't that way. It was a decision made for balance and systemic reasons- They wanted players to seek each other out to craft things for each other, rather than having people with no life being able to max them all and control the market. By not being able to max everything, everyone in the crafting community depends on and interacts with each other, at least in theory. I suppose that some people do use multiple characters/accounts to get around this, but changing it now isn't really fair to the people who are already doing that, as they've spent money on those extra characters/accounts and suddenly not needing to invalidates the work they put into them.
Any changes here would have wide reaching effects on the game economy, both good and bad, and thus would have to be carefully evaluated.