I was googling for some different information when I ran across a document that addresses the issue. In essence, the author claims that while in captivity in Babylon, a new generation of Jews arose who, not having access to the old way of worship revolving around the Temple, developed new ways revolving around the Torah (the Law of Moses). Some of the basic, fundamental, unbreakable rules were
circumcision, the celebration of holy days, the observance of every seventh day (the Sabbath) as a day of rest, abstention from the flesh of swine and other "unclean" animals, and much else. The same text prohibited a Judahite from worshiping any god but the Lord, from partaking of sacrificial food offered to "graven images" (cult statues), and from marrying a gentile.The Jews who had been taken as captives to Babylon developed into a completely different set of people than the ones they were before they were captured. Ezra, having been born and raised in this Babylonian world, returned to Judah and was appalled that the peasant Jews who had been left behind were not the "good, upright" Jews he had known as Jews growing up, and he made it his task to reform them into Torah-abiding citizens.
In Ezra's mind, purifying his people according to the mores he knew was more important than the sanctity of the family unit. And in retrospect, his actions led to a unified, Torah-respecting nation that prepared the way for the arrival of Jesus. As an arm-chair quarterback, I'm not sure I would have handled things the same way Ezra did, but then, as an arm-chair quarterback, I'm not qualified to judge his plays, especially considering that he won the game.