Because some people do not have the gift of tongues so they cannot pray with tongues even when the Spirit is present. Just because you speak with tongues (which means you have the gift of tongues) when the Spirit is present does not mean that everyone in the body of Christ speaks with tongues when the Spirit is present (although they did speak with tongues when they were initially filled with the Holy Spirit). And just because you speak with tongues doesn't mean that you are more spiritual than others who do not speak with tongues.
"Do all speak with tongues?"
1 Cor 12:30 The answer is "no, all do not speak with tongues."
God puts his body together the way He thinks is best. Different people are given different gifts and the diversity is a good thing. It makes it so that we all need one another. Some people speak with tongues and others don't.
I also didn't say that groaning in travailing prayer is the only thing that may be present. I didn't exclude tongues from any type of prayer. I was only trying to show that it is possible according to the scripture to pray in the Spirit without speaking with tongues. The unfortunate thing that would happen if you instructed someone in travailing prayer and said that it must include speaking with tongues is that, if you are wrong, you will make the person who does not have the gift of tongues feel like they are inadequate in prayer because they do not speak in tongues when they travail in prayer. And then they will become discouraged. Instead, you could say that when in travailing prayer they may speak with tongues, they may groan, they may prophesy, etc but to say that they must speak in tongues to be praying in the Spirit is putting an unfair burden on them that the word of God does not support.
It's fine if you don't use
Rom 8:26 as an "only" scripture because I wasn't saying that it was an only scripture. Just as I don't believe
1 Cor 14:14 is an "only" scripture in favor of "only speaking with tongues when one prays in the Spirit".
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