I understand the vast technical limitations and challenges of making cross-data-center play possible when involving data centers from different physical locations IRL. Square Enix does not want to get ISPs and all of their related issues involved for communication between the data centers.

However, I fail to see why they can not do this for data centers that are located in the same building IRL. Wouldn't it be as simple as just using a wire at that point? Why can't Crystal play with Aether?