Yeah, since attachments breaking when you move their parent is apparently a feature
, not a bug, this would be a very welcome addition.
We can't use permanent URLs for our main content pages, because we need them to be SEO-friendly. But the attachments could definitely use permanent URLs, if there were an option to enable that just for them. Then, moving a folder containing 10 pages wouldn't have to entail editing every one of those 10 pages to fix all the attachment links which are suddenly broken.