So quite often orientation has something to do with psychology or power: what do we find most impressive, what do we consider most important. A relatively modern example of such power psychology is the east orientation of a birds eye map of New York and the rest of the world. On this view Manhattan is enormous, the rest of the US relatively small and Asia is a tiny island in the background.
Another reason for not choosing the north orientation is simply because there was no standard for doing so. North orientation nowadays has become a more or less absolute law. But compare it with new technologies: usually it takes a while until a standard is agreed upon (I still have to see a mobile phone which operates like the one I had before).
And another reason for not choosing a north orientation can be based on practical reasons such as the standard size of the paper that was used or the sheet of vellum/parchment. For instance the vellum of a cow is not square but rectangular. So if you have to draw a map of let’s say Portugal one can imagine it is practical to use a west or east orientation: the easiest way to fit Portugal on a cow!