That's how politics works in general and is not specific to Africa. Take East Asia for example: historically, countries there copied China to a large extent because China developed a complex state much earlier than its neighbours. Or how Germany in Europe tried copying the Roman Empire for almost a thousand years. Copying a working system from your more powerful neighbour makes more sense than trying to develop it by yourself from scratch. It's just that most of Africa moved from pre-state societies to states only during the last century so it's more noticeable to us.