At the very least, it would be nice if the “purge by url” supported a trailing wildcard (*).
For example, this would allow purging of all derived images from a WordPress site when an image attachment is modifed/updated:
When you upload, you might have my-awesome-image.jpg, but WordPress creates my-awesome-image-150x150.jpg, and my-awesome-image-300x400.jpg, etc. It would be very handy to be able to purge these with a single API call.
While it’s possible to do the above by querying the attachment metadata in WordPress, it is very possible to have other derivative images which are not accounted for in the metadata, like Retina images and some theme-derived images.