John Piper addresses this in Spectacular Sins, Chapter 5: "The Pride of Babel and the Praise of Christ." His bottom line: because God allowed the building of the Tower of Babel, resulting in many nations, then many nations must be best for Christ to receive glory. Why?
First, he looks at what the sin exposed:
Two Great Inward Sins Exposed Outwardly:
(1) The Love of Praise. They were building a tower into the heavens to make a name for themselves.
(2) The Love of Security. They were clustering together in a city instead of taking the risks to “fill the earth” as commanded.
God doesn’t want us to find joy in our own selves being praised, but in knowing and praising him. Neither does he want us to find security by clustering amongst ourselves, but instead by relying on him, through obedience.
Are we any different than the builders on the plains of Shinar? I admit—I like praise in the right doses, and I do feel secure when I’m in the middle of my family. We’re all still sons of Adam, with our tendencies to rebel against God, deciding for ourselves what is best.
But thankfully, God doesn’t leave us there. For the tower builders, he divided their united front to sin. He set up separate groups as checks against each other’s pride and power. (I’m reminded of the checks and balances in our 3-tiered governmental system.) “Thousands of languages around the world and thousands of different peoples limit the global aspirations of arrogant mankind.”
So, how does this spectacular sin of arrogance glorify Christ? If God permits nothing without a reason, what was the reason for allowing this tower? John Piper lists five possibilities. See if you agree or disagree. I'm still thinking about it.
1. Christians guarded. A diversity of cultures protects Christians against a global anti-Christian state. “God is more concerned about the dangers of human uniformity than he is about human diversity. We humans are far too evil to be allowed to unite in one language or one government. The gospel of the glory of Christ spreads better and flourishes more because of 6,500 languages, not in spite of them.”
2. Pride destroyed. The “pride of Babylon” will always be destroyed. This story is a foreshadowing of the eventual destruction of the pride of all mankind through Christ’s victory.
3. Every group claimed. The power of Christ to make disciples of all nations is highlighted even more when a multiplicity of nations and languages and peoples exists.
4. The gospel glorified. The same is true about the gospel. It is not for one group of people, but fits all people everywhere.
5. Jesus praised. “The praise that Jesus receives from all the languages of the world is more beautiful because of its diversity than it would have been if there were only one language and one people to sing." Revelation 5:9-10; Revelation 7:9-10. Every language on earth gives him praise.
Others' thoughts from Chapter 5 of Spectacular Sins