Promote media details admin page to full post page

[mor10]

Currently when editing media metadata, you either get the modern library modal with the image on the left and various fields on the right. When you click "Edit more details" you get a blast from the past with an old-school version of WordPress admin where everything looks uninspired and, for new users, broken.

Based on user feedback it turns out some site owners use the Attachment Page feature to provide contextual info, commenting, etc for media items. One example was a teacher who uploaded student images to a gallery, then had each image link to the attachment page where further information and images were provided in the "description" field (so the post content) and parents could leave comments.

Since media items in reality are full fledged posts with their own post content, the media details admin view should be upgraded to a full post page with proper WYSIWYG editing for the Description field, custom fields, and ability to control things like commenting.

This would also be an ideal place to visualize in what posts a media item is in use across the site.

[joemcgill]

This seems like something that should start with design discovery, but is a valid problem and a UX pain-point that could be improved quite a bit.