Like most of the other game design choices it is the way it is because the Turbine employee that had command authority used the "Because I said so" rule.
You will run into millions of such examples all aspects of real life. The "Because I said so rule is invoked". After the fact, if necessary, the decision maker will quote those parts of our collective knowledge that aligns with the decision chosen as justification.
For Exampple, you find a lot of this logic in our legal base. The justification is what has been done by peers and people in the past. You pull on that chain long enough you get to the first such example which is "Because I said so rule" which is usually called the precedent. Another common expression "We have always done it this way.".
The inertia imposed by comfort of "same old" via precedent and "We have always done it this way" makes it very difficult to accomplish change. Often times changes only occurs when into a situation where it is a new organization with a leader. No established rules. The leader uses the "Because I said so" rule to define the policies of the organization.
Unless stated otherwise, all content in this post is My Personal Opinion.