I could be wrong, but as our society exists now, the use of the vernacular for the Mass may be the best way to attract people to the faith. It takes a lot of effort to use an English/Latin missel for the TLM, here in the U.S. Our ability to focus on something difficult, without seeing the need for it, is a bit impaired in our fast-moving society today, where most people live in big cities and live a fast-paced life. In other words, we don’t have very long attention spans these days.
If we contrast this with, say, how people were converted to the faith in the past few centuries, the Mass having been said in Latin did not seem to be an impediment. I may be wrong, but I don’t think it was the Mass itself which was expected to be the main instrument of conversion, as it seems to be now. Take, for example, the Native Americans who were converted to the faith. Not only was the Mass in Latin, but they had difficulty with the language used by the priests who tried to teach them the faith. It was the priest who ususally had to learn a bit of the native language, so they could instruct the catechumen in the basics of the faith. One of my favorite Blesseds is Bl. Catherine Tekakwitha. She never saw a Mass in anything other than Latin, and I don’t believe she could even read or write in any language. Yet she had a profound grasp of the faith anyway. Human nature doesn’t really change, but our behavior or perceptions tend to change, or rather, adapt, to meet and conform with Societal expectations, which is different now than in the past few centuries, with the rise of the industrial age (an no, I wouldn’t society to want to return to a pre-industrial mode of living).
So while I think that the use of the vernacular is probably a good thing now, I’m grateful that there are more Latin Masses being offered now for those of us who prefer it.