JJ,
The idea that the Catholic Church requires celibacy because sex is bad couldn't be further from the truth
Priestly celibacy is a requirement of the Catholic priesthood because it is felt that to be an effective priest one should devote ones entire life to being a priest. It is both a sacrifice and a gift. If a Catholic man feels he has a vocation he will be aware that a requirement is celibacy. I am convinced the Holy Spirit gives assistance to would-be priests to enable them to make the sacrifice and follow Christ.
Those who "renounce marriage for the sake of the kingdom of heaven" (Matt. 19:12 NAB) do so not because marriage is bad or second best, but precisely because its goodness makes its renunciation a valuable and generous gift to offer to God. After all, the goodness of a gift determines the value of the sacrifice.
The decision to remain celibate is freely chosen by seminarians, and it is not the Church that is forbidding them to marry. They may choose married or celibate life according to where the Lord is calling them.
In the Gospel of Matthew, 19: 11-12. Jesus says,
"?There are eunuchs born that way from their mother's womb, there are eunuchs made so by men and there are eunuchs who have made themselves that way for the kingdom of heaven. Let anyone accept this who can"
To me this is Jesus himself giving approval of celibacy but he qualifies it by saying, "let anyone accept this who can" i.e., a man who is called to the priesthood.
Nevertheless, at the end of the day, priestly celibacy is a discipline. At the Council of Trent (1563) it was pointed out that celibacy was not a law that came from God but a Church Tradition that could be changed. The Council also went on to say that the Church's position on celibacy in no way minimised its high regard for marriage; the two callings were quite distinct and had their own distinctive demands.
The Church's position today is the same as the Council of Trent. Celibacy is not an essential element of priesthood, in other words there could be a priesthood, which is not celibate, but it is considered an important part of priesthood, and a sign of the priest's commitment to be free of worldly concerns to serve God and his people.