It is clear that God intended the apostles to spread the gospel in native languages. The message of Pentecost. The required latin mass came 160 years later.
I agree with most of the benefits you list, but to say it was beneficial to the majority of people who were poor and uneducated is a fantasy. Until the printing press and universal education people were much easier to hold down and control as they are now.
THIS CHANGED EVERYTHING, made mass communications possible, engendered the first-ever writing in many of the European vernacular languages and permanently altered the structure of society.
This change was not a denominational thing. Gutenberg was a Catholic German printing Bibles 75 years before the beginning of the Reformation.
So the idea that the Mass was in Latin because the priests wanted to keep poor people ignorant, is bogus and ahistorical. An interesting book to read on this is "The Stripping of the Altars," by Eamon Duffy. showing the vitality, literacy, and creative engagement of 15th century Catholic life in England.