I mean, you go to Starfleet Academy to become an officer...just to fix a radio? Come on, now. That's like me going to MIT just to learn how to fix cars. At the very least, communications officer should be seen as a "position" rather than a field of study, which would make the scene of Uhura not knowing Klingon in TUC make sense. Stepping back a bit, the reason why I say Africans are natural polyglots is because your average African knows three languages: mother language, local/trade language and colonial language (maybe a fourth, if English isn't the colonial language, and maybe a fifth, if Islam is part of the culture); same with South Asians.