Mention the word "sex" and there might be various kind of reactions.
People might be uncomfortable with that word and its implications, and hence they react. Some emotions are stirred and people might get defensive.
We know reactions when we see it. In fact, some people on the other side will intentionally stoke the fires, especially when they know we will react. They know if they poke we will coil up and be ready to react in a full way.
But he did use words like "fornication" and "selfish lust" so as to highlight how wrong it was because it was sinful and it was against what God made us to be and what He wants us to be.
Among other things, God made us to be sexual beings and sex is meant to be a holy act that is consummated in the sanctity of marriage.
Yet when human beings forget that the holy fire of love is created by God, then they will turn to immorality and allow the fire into a lust that will burn up and destroy relationships.
Like the five wise bridesmaids in the gospel parable, let us keep the fire of holiness burning bright in our lives.
It would be foolish to let this fire burn out because of a lack of prayer. Because when the fire of God's love is put out by our carelessness, then the fire of lust and immorality will arise and devour and destroy us.