Tongues are not only for unbelievers but also for believers.
1Co 14:22 Wherefore tongues are for a sign, not to them that believe, but to them that believe not: but prophesying serveth not for them that believe not, but for them which believe.
Believers who are born again and filled with the Spirit do not need any kind of sign as they are already acquainted with speaking in tongues.
Notice: prophesying is not a sign to those who believe not but to those who believe!
1Co 14:23 If therefore the whole church be come together into one place, and all speak with tongues, and there come in those that are unlearned, or unbelievers, will they not say that ye are mad?
1Co 14:24 But if all prophesy, and there come in one that believeth not, or one unlearned, he is convinced of all, he is judged of all:
1Co 14:25 And thus are the secrets of his heart made manifest; and so falling down on his face he will worship God, and report that God is in you of a truth.
Tongues with interpretation is prophesying and the "unbeliever" secrets of his heart are made manifest and he will fall down on his face, worship God, and report that God is truly in you!
1Co 14:5 I wish you all spoke with tongues, but even more that you prophesied; for he who prophesies is greater than he who speaks with tongues, unless indeed he interprets, that the church may receive edification.
Notice: he who prophesies is greater than he who speaks with tongues UNLESS he interprets the message that was spoken in tongues.
Tongues with interpretation are equal to prophesying!
How can an unbeliever have his heart exposed unless there is tongues and interpretation? The Holy Spirit is the only one who knows what is in the heart of a person. Speaking in tongues is a person's spirit speaking by the Holy Spirit who knows all things.
Of course, if you do not believe in speaking in tongues or any of the gifts of Spirit you will never see this happen in your Church so in a sense yep you are right these thing have passed away, but only to you and those you fellowship with.
Speaking in tongues with interpretation is for both believers and unbelievers! Praying in tongues to God is for all believers who believe in the baptism of the Holy Spirit.