You can also specify subfolders based on various criteria (collection, type, creator, etc.).
If you have 4,000 attachments, every computer you use has 4,000 folders for them under "storage," and you can't directly view your attachment files all in one place.
Spent some time toying with the file renaming feature and developed this wish list.
Regex is at the top of the list because that alone could address a lot of the subsequent issues. (Though not the URL one because it appears the current renaming for that field, understandably, takes out all slashes, the colon, etc., so it could be nearly impossible to extract just the hostname.)
Provide option for suppressing suffixes where they would create a repeat character, e.g. two hyphens, two periods etc.