I don't get it. What's so holy about Latin?
For the millenium stretching from 1054 to 1970 Roman Catholics shared a common language of liturgical devotion and scholarly discussion. The use of Latin was a sign of Catholic unity and the hymns and prayers composed in that language and incorporated into the Mass are among the most beautiful and impressive literature ever written.
The Latin language is an incomparable treasure of the Catholic faith - as it has been lost, Catholics have lost a large measure of unity, orthodoxy and their sense of historical mission and heritage.
Latin was extremely practical as well - as the official language of the Church it shows no bias for or against any modern tongue. Because it is no longer used as a language of casual conversation, its semantic content is much more stable - it is hard to twist the meanings of words in Latin anymore.
Its use in the liturgy was a signal to Catholics that they had entered into a different place, a divine sanctuary. The worshipped in a language which they associated with sacred worship and the sacraments.
The study of the language was an excellent, broadening experience for young Catholics, and knowledge of Latin increases one's level of culture and intellectual discourse.
Latin is still kept as a sacred treasure of the Church by many - it's return to its rightful status as the common heritage of Catholics is a consummation devoutly to be wished.