Same thing that Santa Claus does for Jesus. Catholics are joyful people who like their religion, like Jews. It's a culture that starts in childhood and goes on through life. The Easter Bunny is a childhood story that makes the kids happy and makes them look forward to Easter, and happy, and allows families to have fun together on the biggest feast of the Catholic calendar.
The Easter bunny is to Easter the same thing that a big glazed ham and the lilies and the pretty dresses and the singing at Church all are: part of the fun, part of the celebration.
Non-Catholic Christians are usually dour, bitter, sour people, who think that anything fun is wrong. So of course they hate the Easter Bunny. Puritanical types all have Aspergers.
I have issues with the Easter rabbit even being associated with Passover; a holy day ordained by the Lord. It is my understanding that Passover and The Ten Commandments never originated from Christianity as Passover and the Commandments were prescribed for the Jews. The idea of hiding fertility eggs and celebrating something the opposite of what the Lord had intended Passover to be, is something Jesus would never approve of. Just ask yourselves, "What would Jesus think about this?" If you have sought out this question carefully eventually you will find your answer.