The sex drive has always been strong, but promiscuity used to be considered morally reprehensible by most people - today promiscuity is largely accepted as part of life. And as such the Church requires its priests to be witnesses to selfless sacrifice - which is one great benefit of celibacy. No one is forced to be a priest. No one is forced to marry. But those two commitments require one to make a lifelong promise about one's sexual behavior: chastity. Priests know when they make their lifelong promise that chastity means they promise to remain celibate for life. It is a wholly voluntary promise and they are not forced to be ordained.
The sex drive like many other appetites (with the exception of eating) loses its pull on a person when they don't engage in it for a long period of time. Most people require affection for sex to be satisfying; one night stands or casual sex do not provide much of this sought after component; especially in people over the age of 25 or 30. Having sex for the sake of the act itself is no different than eating when you're not really hungry. Too much of that and you become fat; too much sex without meaning and you become hollowed out. Celibacy is not that hard in my opinion; once the intital period of adjustment has passed.
And in such a society , all faithfulness to vows are thought foolish.