Why did imperial powers create spheres of influence in other regions instead of creating colonies?

Some simple reasons for this could be that it is easier to manage spheres of influences that to manage a a system of colonies, and it is cheaper. The costs of running, occupying and defending colonies was high. You can get political, diplomatic subordination of weaker nations and trade and economic advantages in a spehere of influence, without having to occupy those countries militarily. This is a simple analysis maybe, but it seeks to highlight some pragmatic aspects.