Seriously? How many years have to pass so that we can have a sane default behaviour regarding extended attributes in mv and others? Do you consider it as a Wishlist bug? Like, if most people don't use extended attributes now, it is just because there is enough risk to lose their precious data if they use extended attributes. A significantly useful feature of filesystems is not used by users just because userspace commands and tools are not supporting them properly.
As far as they don't support and perserve extended attributes properly, this feature does not practically exist! Better say there is no user-xattr in gnu/linux at the moment. Blessings...-- Best Regards, Abraham Sent with Tutanota; https://tuta.com