"Maybe I am wrong, but I heard that even at Vatican I many bishops had a hard time communicating orally in Latin."
Another means of separating the wheat from the chaff, perhaps.
Newman once commented that the problem was pronunciation. An Englishman could not be really fluent in Latin IF he had to adopt an italianate pronunciation. And if he tried, the Italians would simply sneer. Latin was better as a common written means. sort of like Chinese writing is common currency between northern and southern Chinese.