Our 2 yr old learned to crawl out of his crib too, but we have worked very hard to teach him obedience when we tell him something is not okay. He now seems to understand that crawling out his crib is dangerous-or at least that we don't like it. Since learning this he has never attempted to crawl out of his crib. He seems to really crave the security of his cribs sides. He does not sleep well in a regular bed. Perhaps your daughter would prefer the crib side back on.
Just remember that boundaries are a source of security for toddlers. They are constantly testing you to see if their boundaries are secure and safe. I would think that even a crib rail could be one of those secure boundaries? Not sure... I just know that our toddler really likes the sides there.
Oh, and one more thought. Is she still napping during the day? Sometimes too many naps can make sleeping through the night rough. I would recommend trying to skip naps if possible until she is sleeping well at night. Then only allow short naps.