Currently, if one of the Legacy Bridge commands fails to create relative symlinks (with --relative flag), they fall back to hard copy. Because the hard copies need to be created again when anything inside is changed, the absolute symlinks are a better option. So, the Legacy Bridge should fall back to absolute symlinks instead.
Being unable to create relative symlinks is something that happens often on Windows, but can also happen in other circumstances.
The default behaviour of Symfony commands is also to fall back to absolute symlinks if the relative ones cannot be created (ref.: https://github.com/symfony/symfony/blob/eca17ec964175cb6bc35756a0a20767e84333cca/src/Symfony/Bundle/FrameworkBundle/Command/AssetsInstallCommand.php#L189).