Rational Catholicism believes that man has a definite nature ultimately fulfilled only by adherence to, and union with, his creator.
There's just one Catholicism. It's headed by the Pope. You believe what the Church believes, or you don't.
Faith is not an exercise in rational thinking. That's not to say that it's irrational or illogical to believe in Catholicism.
Simply that you do not arrive at the Truths of the Catholic Faith by by-passing Faith.
That sort of goes without saying.
But liberal Catholics don't get that.
Given that Vatican II stated that a vocation to virginity is not inherently superior to a vocation to matrimony,
It is a dogma of the Catholic Faith, defined at the Council of Trent, that virginity is a superior state than matrimony.
What does that mean?
It does not mean that celibates are automatically more holy than married people.
What is means is that celibacy, when lived properly, is a state of life that is a quicker path to holiness.
It is even stated in the New Testament.
Celibacy makes a person more free to pursue one's spiritual quest. That should be obvious to anyone who is married. If you are married, you are busy with your marriage, your kids, you mortgage and everything else involved with being in the world.
If you are celibate, you do not have to worry about a relationship with a spouse, nor about raising kids.
That leaves you with a heck of a lot of free time to engage in other pursuits, such as prayer, mortification, works of mercy, ministry and the like.
The celibate life is intended to make a person more focused on Jesus.
It is the difference between an athlete who trains only in his spare time, or one who trains full time.
Naturally, he will be a better athlete.
Married people can of course spiritualize their daily life, but it is a more difficult path, given all the concerns associated with having a marriage.
Celibacy is a calling. It's not for everyone. It's like any other talent or disposition: some people got it, and some people don't.
it is not clear that there ever was a convincing theological case for a celibate priesthood; rather the arguments are pragmatic and traditional.
Well, given the explanation of the above, I think the theological explanation is quite convincing.
Somebody who is more focused on Jesus is a better candidate than those who are less focused, all things being equal. I think that goes without saying.
However, requiring celibacy
We have to change our language about priestly celibacy.
The Church chooses to ordain those who have a vocation to celibacy. Jesus said that what the Church binds on earth will be bound in heaven. If the Church chooses among the celibate, God works with that. And so God calls only those who have a vocation to the celibacy to the priesthood (in the Latin Rite).
Therefore, it's not a matter of "requiring priestly celibacy". It's a matter of finding those men who have a vocation to celibacy, and then ordaining them to the priesthood.
As for the issues about knowledge of marriage, etc those are secondary.
First and foremost, you want holy and orthodox priests.
Knowledge about marriage can be acquired. First-hand knowledge of marriage can also be a negative thing, because your view of marriage is so coloured by your own that you tend to work from that rather than from what works.
There are married clergy all over the world. Does the fact that they are married produce better marriages among the faithful? That can certainly be questioned.
Which misses entirely the crucial point that celibacy is neither a necessary nor a sufficient condition for being a good priest.
But holiness is an extremely important one, though. "Rational" Catholics tend to downplay the power of Grace and the supernatural.
That's why they often lack faith.