As noted, it is only mandatory in the Latin Church. Just curious to know why you feel this way.
The policy was instituted in after the Middle Ages largely as a response to rampant corruption in the Church, primarily nepotism and simony. I question whether it is still necessary. Many Catholic priests are already married. And they do just fine. Mandatory celibacy should not be a requirement for service in the priesthood. They should be free to marry if they want.