There is no such thing as the gift of tongues. The word gift in KJV is italicized, indicating that it was supplied by translators. The word 'spiritual' proceding gifts could and should be correctly translated 'matters of the spirit'. Tongues are not a gift; holy spirit is the gift. Speaking in tongues is one demostration of the gift.
Tongues were genuine languages, not ecstatic utterances.
1Cr 13:1 Though I speak with the tongues of men and of angels, and have not charity, I am become [as] sounding brass, or a tinkling cymbal.
Clearly the Bible teaches the possibility of languages of men and angles. But nothing says that the hearer will necessarily understand anything spoken because he that speaks in tongues doesn't speak to men but to God.
Tongues were a sign for UNBELIEVERS, not believers.
Yes. Speaking in tongues is also prayer in the spirit as God giving the utterance. Speaking in tongues is also praising and speaking the wonderful works of God, and it edifies the speaker. Kind of makes me wonder why you wouldn't want to do these things and work so dilligently to keep others from doing them as well.
If you deny any of the above points, you deny the clear, plain teaching of Scripture.
So why do you deny clear scripture that tells us to speak with tongues? There's no harm in it and many benefits.
What motivates one to talk people out of the clear teachings with clear blessings for those who choose to believe?
Go back and read again, please, there was plenty of Scripture to back up what was explained.