Honestly I didn't even notice the change until later on and the more I think about it the sillier it becomes. It actually made sense for her back to be exposed due to her wings. Sure you can just assume there's some sort of tiny holes in the back for her wings but you never had to consider that with the original. It was practical for those that didn't think much of it and sexy to others I guess. Literally best of both worlds.

If it doesn't matter, why change it in the first place?