The biggest problem in having the Bible only in Latin was that most of the people were not able to understand it, thus it was harder for them to accept the Christianity willingly. The Latin was the language used in the Roman Empire, and was also spoken by some of the aristocrats of the other countries, but for the wider masses it was just a foreign language that they couldn't understand, so even if someone else was going to read them the Bible it was in a language that they didn't understood.