That tongues is a prayer language that is more effective than your native language.
That Satan cannot understand it because it’s a heavenly language and therefore, when you pray in it, Satan cannot use what you are praying about to attack you.
That it’s for every believer.
There’s the doctrine of the evidence, which is that speaking in tongues is evidence that you’ve been been baptized into the Holy Spirit and that if you don’t speak in tongues, that somehow your fullness of the Holy Spirit is somehow lacking. There ends up being class distinctions within churches between the haven’t and the have not’s and the have’s are more spiritual than the have not’s.
That believers should seek to speak in tongues.
There is very definitely a tendency for Christians with the gift of tongues to get carried away. Rather than arguing with them, prayers would likely be more effective. The Holy Spirit’s job is to convict people of sin and error. Whereas we are not (like, for instance, Paul to the Corinthians), the spiritual mentor of the tongue-speakers, they are more likely to listen to the Holy Spirit than to us.
There is little question that the Corinthian church was the least mature of the NT churches. They also enjoyed the widespread gift of tongues. Whether there’s a correlation, God knows. But this we know: immature Christians are error-prone. Rather than condemning them, we should pray for them. That is our response of love—and as you said, love is preeminent.