This is not due to ignorance, as I speak German, some French, and some Italian (having lived in these countries while in the USAF). I've been to the Vatican numerous times and have been in Mass led by the Holy Father (who spoke it in several languages). Most of my parish, however, speak only English. It helps their faith to understand the words and teachings laid out by the English-spoken Mass.
Actually, it is likely that Jesus had at least some Latin as Jerusalem was a very cosmopolitan city under Roman control. Recall that He had no trouble communicating with the centurion who sought healing for his daughter.