The main selling point with this type of interface that not everyone immediately understands is that "content blocks" are WP's default content types plus any CPTs you add. This would allow WP to function more truly as a CMS without doing anything that isn't good for blogging as well. It would just be a lot easier to craft your own content model where content types can be re-used and moved around within other content types, and each type of content could have its own taxonomy or share a taxonomy with other content types. Several good new-ish CMS projects were born partially out of frustration with WP (and others) on this point. I think Expression Engine has always been attractive to a certain type of marketing and content focused user because it makes it easy to re-use content and define many-to-many relationships