Border of Mauretania Tingitana

[Epictetus]

I think that Rome was often reluctant to assume direct control unless absolutely necessary. In Anatolia, for instance, there were some cases where Rome actually surrendered areas they directly governed to client kings, only to re-take control when the client kings couldn't handle the situation to Rome's satisfaction. It is much easier if someone does what you say instead of having to do it yourself. ;-)

On a semi-related topic, there was a discussion about North African borders in this thread that you might find interesting.