Its like how they did it in XI, which I remember there being quite a diverse list of words to combine from there. I'd say its to avoid racist/rude names, which may well be a reason, but then we also get freedom in choosing our company chocobo's name so that doesnt make much sense.

Unless it's BECAUSE we had freedom with the company chocobo, so many terrible and disgusting names, they decided we aren't mature enough to choose our own names anymore ._.