Christ said that some "have renounced marriage for the sake of the kingdom of heaven" (Matt. 19:12). And remember, St. Paul regarded marriage as an option and not necessarily the best one.
And some of us got married "for the sake of the kingdom of heaven." In God's design, the norm is marriage, family, childrearing. This is what He expect the vast majority of the time, and is His highest calling for the vast majority of people. Granted, there are exceptions that "test" (the older meaning of the word "prove") the rule, but their vocation is different, not better, not higher, not "more spiritual." Paul, I believe, addressed a specific era, a time of intensified persecution. Those are not normative times. Like newspaper headlines, they get attention for deviating so far from the normal rhythms of life.