To recap, every post is stored in the wp_posts table and revisions have a post_type of 'revision' and a post_status 'inherit' (attachments also inherit). There'

To recap, every post is stored in the wp_posts table and revisions have a post_type of 'revision' and a post_status 'inherit' (attachments also inherit). There's no gradual improvement you can do to this. More, their codex does not discourage accessing the database directly at all rather points out there's a class to make it easy https://codex.wordpress.org/Database_Description https://codex.wordpress.org/Database_Description so moving revisions to a separate table will break every plugin which wants to access revisions and uses the wpdb class to do so which is just not acceptable: "WordPress strives to never break backward compatibility. It’s one of our most important philosophies, and makes updates much easier on users and developers alike". We can have debates about whether this philosophy is the right one or not but there's no point. It's what it is and it makes fixing things like this simply not possible.