See the African Map? How long does it take the people of Morocco , Senegal, the Gambia, Ghana Tunisia, Sierra Leone, Liberia etc. to travel to South Africa. or Ethiopia ? Very long, too long and too costly in term of plane fuel or plane tickets.
So let's get out of those so called historical considerations and talk about efficiency by relocating the African Union Headquarter from Ethiopia to Northern Democratic Republic of the Congo, and relocate the Pan-African Parliament from South Africa to Central African Republic

Is your CAR gonna foot the bill? Currently SA foots most of the bill for PAP.

And what historical considerations are you talking about? SA began hosting PAP in the late 2000s whilst central and worst africa snoozed - not 1920.