Bava Kama 82 quotes 10 takanos that Ezra made:
עשרה תקנות תיקן עזרא שקורין במנחה בשבת וקורין בשני ובחמישי ודנין בשני ובחמישי ומכבסים בחמישי בשבת ואוכלין שום בערב שבת ושתהא אשה משכמת ואופה ושתהא אשה חוגרת בסינר ושתהא אשה חופפת וטובלת ושיהו רוכלין מחזירין בעיירות ותיקן טבילה לבעלי קריין
The Ohr Sameiach (Issurei Biah 4:8 last paragraph) makes an interesting observation. He writes that the gemara has many takanos, many dinim derabbanan, but these were primarily instituted for “tikun ha’dat.” They preserve and protect the rules of the religion, the halachot d’oraysa. For example, Chazal made a takanah not to swim on shabbos lest you come to make a raft and violate a melacha. The takanos of Ezra are different. They were primarily instituted for the sake of “tikun ha’umah.” The purpose of the takanos was not to prevent a person from a religious failing, but rather the purpose was to strengthen the social and family structure of the nation.
One of the challenges that Ezra had to deal with when the Jews returned to Eretz Yisrael was the high intermarriage rate. To put it crudely, marrying a shiksa was the norm. Ezra responded by trying to strengthen marriage to Jewish women and make it more appealing and attractive. That’s why he instituted selling perfume to the women, that’s why there is a takana to eat garlic for the sake of onah on shabbos, counterintuitively, that’s why he made the takana of tevilas Ezra, as the gemara writes, so that “talmidei chachamim should not always be with their wives.” Too much familiarity is not always a good thing; a little seperation preserved the desire to be together when allowed.
From Divrei Chaim, here.