Yes, I agree, the bedroom is a private thing and should be so. Brother Paul would agree. Yet here he, in the Word of God, is giving a commandment: "defraud not" your husband or wife. Preachers should be preaching this. Why? because God thought it important enough to have Paul pen it down in the Word of God. That is not an intrusion into anyone's personal bedroom; it's a general command given to all married couples. Neither should any man intrude, in anyway, verbally or otherwise into one's married sex life. However, the Bible does say that "aged women" are to teach "younger" women to love their husbands. I wonder why that command was given to "aged women"? Because experienced, Godly ladies are the only persons qualified to do so.
Yes, Paul says he wishes everyone were like him, apparently unmarried; I get that. But in verses 3-6 he is specifically addressing those who are already married. Those who do decide to get married do not marry solely for platonic reasons. If that were the case, why not just live with the same sex? I say that it's normal, and God made us so to have sexual attraction to our mate at the beginning, I mean; that's why he made us "male and female". But then the couple is meant to grow closer and deeper in "agape" love as time goes on. So I agree, a marriage which continues to build on nothing but sex, cannot succeed very well at all. But a marriage IS based on sexual attraction/desires. Like it or not.