God used the occasion of Shavuot (50 days after the Passover during which Jesus sacrificed on the Cross) to bring an audience of many earthly nationalities of Jews to the apostles, who were gifted with praising the Lord in the earthly languages, spoken by this audience, that they did not know.
This presaged how the gospel message was going to go out through the entire world, first to the Jew then to the “Greek” (gentile).
When modern Charismatic churches praise in tongues, this worldwide reaching aspect of the will of God should be in the forefront of the minds of all who witness it. And when non-Charismatic churches read the passage, this should also be true of the minds of all who hear the passage.
Acts 2 is there to show us that the gospel should be preached throughout the world in whatever manner the audience can understand.
Spot on: The purpose of the many tongues was solely for the purpose of proclaiming Jesus Christ as Son of the living God, Crucified and Risen.