Just so that you know, I am not arguing for solely single pastors! I fully believe that most men should be married and that we should follow the biblical mandate "to be fruitful, multiply, and fill the earth."
I just do not see a litmus test in regards to a pastor fitting that narrow mold that you have suggested.
Even a single man has an "oikos" and he must rule it well.
And, you have innocently disqualified a great number of pastors from every stepping into the pulpit because they may not have children for any number of reasons, infertility, lack of finances, just not the proper time yet, age, or some other reason. If that is what you are truly saying, then there is a lot of re-arranging to happen in the church across the world, and as i anticipate your response, that would be fine with you because you most likely feel that your current church expression is the correct one and all others should mirror it.
Dare we divide Scripture on this issue, where both Jesus and noted apostles, some of whom were called "elder" were not married yet both carried out church work, pastoral work, church planting and missionary work, and also said that it would be best for the sake of the kingdom if a person was not married. Marriage is great. Perhaps God's greatest gift and according to Paul the issue most like Christ's relationship with the church (Eph 5). But perhaps not required for all who might lead God's church.
I am merely leaving open the potential that a rare few might indeed have that gift of celibacy and can yet lead God's people. That does not even mean that I advocate the practice -- I don't -- but only that it is possible.