The Sacred languages of the Cross-- Latin, Greek, and Hebrew (in addition to the late Aramaic derivative in Syriac)-- are falling into oblivion while giving way to the modern languages as the exclusive medium of liturgical worship.   

The case has been made (quite one-sidedly) for accessibility through adaptation, and it is true that St. Peter in his missionary days did not preach, much less worship, in Aramaic but in Greek (and somewhat in Latin) among the early Christian communities of Rome (Indeed, why would you go live among the Romans and speak Aramaic which nobody, including most Hellenized Jews, could understand in the West? )

Pastorally, practical necessity is a law in and of itself.  That was true of 1st century Rome as it is of 20th Century Chicago.  It is just a reality, and one can accept it or do something rather foolish by resisting what is beyond their control.

That said, vernacular slippage in both theology and liturgy is a messy reality (e.g. think of the tragic debate on the title of "co-redemptrix" in Latin vs. English and the theological red herrings that monolinguistic biases alone create!).   Also, St. Peter's Church was necessarily one of converts (not people born into and raised in the Faith).  So the analogy between what he did and we should do can be fairly tortured.  Ours are NOT the days when Christianity is a novelty.  If anything, it is quite old.  We are not beginning from scratch, and it is rather impious to believe otherwise.

Right now, the danger of theological (and moral) debasement is especially true as the modern world becomes notably different from the days of Christ.  Think of the agrarian parables of Christ: can children who don't even know where milk comes from understand His sermons?

This incongruity that is all too quickly bridged by sloppy translation (both in word and deed) poses general challenges, I would argue, because the modern vernacular carries with them certain connotations, tonal-emotive textures, and background associations that risk profaning the sacred rites, distorting doctrinal lessons, and the overall intentional purity of our worship as handed down from one generation to the next.  And without the requisite knowledge of ancient Christian languages, how would you even know that you are distorting the truths of theology whether doctrinally in what is being taught or liturgically by how the faith is practiced?

The point is that you wouldn't even know.

That is a kind of countervailing truth in favor of traditional sacred languages that balances against the more obvious demands of practical necessity alone.  Sometimes, we have to learn about the Faith with effort and attention of much diligent reading and introspection--- and yes, actual prayer--- rather than having it spoon fed to us like babies.

Using the vernacular in the most numinous of moments in contact with the Divine can also distract by reminding the worshiper of the outside world at a time when they should not think about the World at all.   

That is kind of the crux of the matter (pun intended!)

Even so, such insights have not been regularly appreciated by liturgical scholars or theologians who believe that Pentecost is an ongoing rather than historical event.

In this place of the blog, I meditate upon the old ways of saying things (and occasionally the old ways of doing things) where it seems most relevant because I believe the most valuable things in life are inherited and passed down in a carefully curated way (How you pass down something of value from father to son to grandson says a lot about what that family values.  And some people gift nothing other than money, which is done in the name of "accessibility", but how is that not a sign of a crisis in meaning (and family) in itself!).

NOTE: This isn't to champion antiquarianism or "worship of the past" (as that would be an idolatry disguised as godliness); after all, the clearer Trinitarian formula of the Latin-translated Creed has the theology of procession more in line with theological reality (even when the Creed was originally in Greek); for this reason, original isn't always "better".  Allowances for development are necessary, but one should not neglect their spiritual heritage in the name of "relevance" either.  There is such a thing as a Pyrrhic Victory in keeping things "relevant."  And, beyond all doubt, there is also such a thing as erring by two extremes. 

Curation of what is passed down from one generation to the next means that we distinguish the clutter of our lives from the meaningful objects of true sentimental value that we decide to pass on, and it implies that some things will be discarded or not inherited.   Otherwise, you just get a mess!

That insight is important when reflecting upon Tradition in a faith tradition that consciously develops.

Being moderate in such things requires then some knowledge of the old languages (and old practices): why else then do we have a special term for the Eucharist's real presence called "transubstantiation" that is from Latin?  Imagine talking about the Blessed Sacrament without the aid of Latin!?

For that reason alone (but hardly just for those reasons alone!), the old languages matter.  You don't have to be fluent in them.  You don't have to be a scholar.   It is just a good penitential practice to learn them and also spiritually expedient.