Hey Cathode.
Sorry it took a while to reply.
I used to go to a Pentecostal church for a while, and I am familiar with all the stories and attempts to justify tongues for today. While it is true that we should always seek to edify the Body with the gifts, for the sign gifts, the sign was always the primary purpose. The edification part was secondary to keep the gifts Biblical while the sign was being given. Paul tells us in 1 Corinthians that the purpose for tongues is for a sign, that's it's primary purpose. And we also see in Scripture that it was a sign of judgment.
Paul also said that prophesy is better, because it naturally edifies with out interpretation. "speaking before" isn't speaking of before in time, but before people. That's all it means. While Prophecy could carry the idea of new revelation, for us today, it simply means sharing what we already know.
Another problem with tongues is that it's not happening today. For all the attempts and the fantastic stories, Pentecostals and Charismatics still send their missionaries to school to learn the languages of those places that they are to evangelize as missionaries. I've heard all those same stories, even the healing stuff. It's just stories. I would not recommend chasing "signs" as Israel did, Jesus, in Scripture is always rebuking that kind of faith. The Jews want a sign, and Greeks want wisdom, but we preach Christ crucified..., Todays Pentecostal/Charismatic churches perfectly exemplify the Jews seeking after a sign, in my opinion.
I think where the Charismatic/Pentecostal church's really miss the boat is in understanding that anything good that comes from us for the Body/Church is a gift from God. The lists of gifts from the Holy Spirit in Scripture were not exhaustive. Jesus said that He is the Vine, and we are the branches, and without Him we can do nothing (nothing good is implied). God alone is good. "What do we have that we did not receive..?". The flesh cannot produce anything good by righteous standards, thus it's a gift from God. That's why we give God all the credit and praise, because He actually deserves it.

That's the way that the gifts should be understood.
At a certain point in time in history, there were sign gifts. These had a point, they were for a sign. The secondary benefits were just to keep them edifying, and not causing confusion. When the primary purpose went, the secondary benefits went with them. We no longer need the sign to unbelieving Israel, because the judgment that it pointed to already happened. The healing and miracles was to confirm the message and the messenger when that new revelation, the Gospel, was being revealed.
Also, if you remember, at Babylon, they tried to storm heaven, and as Judgment, God scattered them and confused their languages. Before that there was one language. What happened at Pentecost was kind of an undoing of that judgment so that the Church could evangelize the world. At Pentecost, they knew what was happening was from God because only He could lift that road block. It was a confirmation, of sorts, of Who it was from and what was happening. At Pentecost in the example that you gave, them hearing others from other countries speak in their own language. Barrier removed, supernaturally. It's from God.
A modern example of tongues, or languages as judgment, is right here in the U.S. today. Can you see the parallels? There is no longer one language, nor is there even an attempt to preserve it. As a Christian nation, as we once claimed, one could easily take what is happening today as a nation under God's judgment, and the foreign languages taking permanent root could be considered a sign of that judgment. It's very similar. There's not magic to it.
Are you Catholic? I had heard that these things have taken up root in Catholicism.
Dave