Right, but your argument is that it should be in the game, but why does it have to be in the game? It doesn't have to be in the game.
I can understand you saying that you would like for it to be in the game because you are interested in it. However, your premise from the beginning seemed to be that it has to be in it because African cultures, etc. are underrepresented or that there is something wrong with the fact that it isn't in the game.
Again, it boils down to what people are interested in. Most of the players are interested more in European factions and the company itself is from Turkey so you can see why the factions that are in the game, are in it. There is no crime committed here by them doing it this way.
More factions are great, I would prefer a different faction than an African one. However, I wouldn't mind any faction that they added. Personally, I would love a more viking faction than the Sturgians. I would also love a Japanese themed faction, but that definitely isn't happening.