What types of circumstances would encourage management to establish a complex organizational structure?

When the assets of the organization increase to such an extent that it would be difficult or less profitable to directly manage them, then the organization employs a structured system which would become complex eventually.

The complexity mainly arises due to increasing manpower and expansion of marketing regions (targeting new countries, new markets). Also, in order to sustain the establishment towards various market risks and obstacles, it would adapt and evolve to a better system which ultimately becomes a complicated system.