The gift of Tongue is a important gift for every believer. In fact it is so important that it is the first gift the Holy Spirit gives to a believer, immediately He fills the believer (Acts 2-12). But unfortunately, many believers are missing out of the immense benefit of this awesome gift of the Spirit as a result of unbelief.
Now contrary to your suggestion that the gift of tongues is insignificant, I want to prove to you that the gift of Tongues is very much as important as other gifts. And I'm going to do that with my personal testimonies...
By the operation of the gift of Tongues in my life, the sins I used to struggle with, I now overcome them cheaply. In short, on one of such occasions, I was attacked by a very strong spirit of lust towards a sister I was prospecting to be my wife. Then by the leading of the Holy Spirit, as I engaged violently in speaking with other Tongues, I received an instant deliverance that made the lady seem like every other person to me, the next time I saw her.
Just last month here (May) as I prayed in other Tongues, I got a leading by the Holy Spirit, to pray for my friend who was sick over the phone, and as I prayed for him, he was instantly healed. Also the same last month, I was praying out loud in other tongues in my house, and as my neighbor overheard me, she placed her hand where she was having pains and was shouting amen, each time I concluded my Tongues prayer with the name of Jesus. And by daybreak, she was totally healed of the pains.
Some time back, I was given a fairly used Laptop as a gift, and it had challenge with the flex. But then, I didn't have any money to take it for repair, so I prayed in understanding, then in other Tongues and the Laptop worked for up to one year.
I can go on and on, giving you the testimony of the Lord which I got as result of taking God at his word and speaking in Tongues by faith.
Then for the Interpretation, The Apostle Paul said, if we speak in Tongues, we should also ask for the gift of interpretation. I asked and I received it by faith. And from time to time, as I pray in tongues, I open my mouth in faith for the interpretation, and I do get great messages from God through the Interpretations. Then at some other time, as I minister to some people, and they are attacking me with questions, as I speak in Tongues, the Holy Spirit inspires me with the right words and scriptures to reply back to them. And of course, many of those inspired replies are the interpretations.
You see many people have the gift of Tongues and Interpretation in them, but because of unbelief and religion they are not able to appropriate them for their profiting. And I think it is so because they don't believe they are achieving anything as they don't understand what they speak. And also the interpretation follows the same pattern as the Tongue itself. The interpretation of tongues is the prophetic inspiration you receive, when and after speaking in tongues.
And many a time, people do interpret, but they do not know, they are interpreting. When you say something edifying that you did not premeditate, after speaking in tongue, that's the interpretation.
To learn more about this topic, get Kenneth E. Hagins Book: "Tongues Beyond The Upper Room"