The typical answer for old behemoths: it was built because it was necessary to build it, and it won't change until a change is necessary too. Wanting that chang

The typical answer for old behemoths: it was built because it was necessary to build it, and it won't change until a change is necessary too. Wanting that change is not enough, it has to become an almost mechanical constraint, and usually the constraint gets noticed when it far outweighs the costs (and not just a little). Or is a noticeable threat to the system's existence.