So right now we mainly have 3 kinds of roof colors: black, white and stone grey. While this may be enough to build many airports in the US and EU, it becomes insufficient when creating some Asian airports, especially large hubs with immense terminal size. The current terminal roof looks dull with limited texture to choose from. As building a custom terminal is extremely time consuming, providing roof texture with more color options can be very useful to enhance the current “lego brick” terminal looking without the need to fully rebuild them.
Here’s a concept of ZBAA Terminal 3 with realistic orange color roof, powered by Photoshop:
This is next level realism compared to current stone roof.
This can also be applied to other airports like OEJN (orange), RKSI (cyan) and many other airports that have colored roof.