I also have this problem. after migrating some assets to a project, packaged size increases even if assets are never used. Is there a way to avoid this? I would like to be able to have assets available in content browser in case i would like to use them, but not increase size of final game if not utilized. I am packaging for windows only at this time. Hopefully this can be resolved as it is rather disruptive to workflow to have to hunt down individual items for import in an effort to keep release size to a minimum.
EDIT: or, an option to select items in pending deletes that that have references, and remove them from pending deletes? That would help me greatly in process of cleaning up a project.