However, this is a secondary benefit and it is not essential to human relationships and affection in general; we can deeply love a person without ever having sex with them.
If what you say is true, then what about Ex 21:10-11 "if he takes another for himself, her flesh, her clothing,and her conjugal right shall not be diminished. and if he does not do these three for her, she shall go out for nothing, without money." ( interlinear by J P Green) In this case it is not saying that unless he gives her a child she is free, but rather if he does not care for her most intimate needs (sex), she is free. That places the need for fulfillment in this matter (sex) right up there with food, shelter and clothing.
Some times it may be that due to our personal needs or sex drive, we see the matter as you are describing (just a secondary benefit), but that is not true of everyone. Why is fornication and adultery such a major issue in society, world wide? Even among those who claim Christ. It is true that we can love someone without having sex with them, but if that relationship is close enough then that desire can also burn like a fire, it may never be accomplished, but its still there and can have a major effect on the one afflicted by it.
At a personal level your thinking and position are fine, as that is between you and your wife, but when it comes to instruction others to follow the same line of reasoning, that is fraught with danger.
1 Cor 7:2 "But because of the temptation to immorality, each man should have his own wife and each woman her own husband. The husband should give to his wife her conjugal rights, and likewise the wife to her husband. For the wife does not rule her own body, but the husband does; likewise the husband does not rule over his own body, but the wife does. Do not refuse one another except perhaps by agreement for a season, that you may devote yourselves to prayer, but then come together again, lest Satan tempt you through lack of self-control.
Paul is not talking about having children or some insignificant little need that is easily controlled. Rather he is saying that this matter is such a base need for people that it should not be dismissed.
My concern is that this line of reasoning is not in harmony with the apostle Paul's counsel, as the needs for fulfillment (sex) is being presented as a secondary need and the responsibility to procreate is primary.
What if a couple read this instruction and we will say the husband agrees and see the need for sex a only a secondary need, but the wife over time comes to a different point in her life and then strays, would we not then carry some responsibility, before God for interfering in matters that are between a man and his wife ? For many sex is no secondary need but is a primary need and must be fulfilled and I believe that this is one of those matters that is between a man and his wife and we need to be very careful when we start to give advise that does not align with the comments of others such as Paul.
The instruction from the scriptures is there for a reason as we are all different with different needs wants and desires. not everyone will see things as we do, the issue comes in when we try to instruct others according to our own needs or thinking.