But Jesus was unmarried, we have no certainty that Peter's wife was alive by the time of the Gospel, and then there is the whole issue of becoming "a eunuch for the sake of the Kingdom" among others.
I don't have time to explain all of the reasonings, but here is a document written by Pope Paul VI that gives explanations - some theological, and if I recall correctly, some practical.
Yeah? So? That's really irrelevant. By that reasoning, everyone who is a believer should remain or become single.
Besides, Jesus healed Peter's mother-in-law and in Acts, some years later, Paul refers to Peter having a wife.
I Corinthians 9:5 Don't we have the right to take a believing wife along with us, as do the other apostles and the Lord's brothers and Cephas?
Besides, What's the big deal about priests remaining unmarried? God never demanded that of the Jewish priests who served in His temple. Jesus never taught it in Scripture. It doesn't make any sense that they'd be better priests if they remained single. There are plenty of successful ministers and missionaries who serve God who are married. It didn't interfere with their ability to minister.
My argument with it isn't that the Catholic Church doesn't have a right to decide that for themselves, but that they don't have any good reason for it because there's no Scriptural precedent for it and it's putting a burden on those men that they don't need to bear.