Africans are less copied because regarding for example Europe there was never a fascination for Africa as there was for the US (again, AAs are Americans). African culture/music/style was not "hype". Plus African countries do not have the necessary market to support cultural products at that level, as opposed to American corporations who cashed in on AA culture and had means to export it. Now that African culture is more developped it's starting to get more hype in Europe (music, theatre, dance, fashion).
By developed, you mean taking a Western pop approach to its music. When you adopt dancehall, soca, rnb, cuban rumba, rap and house sounds into your music then it becomes way more palatable to Western audiences. It isn't just because there are more platforms to reach a wider audience. Even still, I don't see any African nation having any kind of run similar to what we've seen here in the States though I do enjoy Afro pop.