Have you seen ‘Durin’s Folk’ edit by Maple Films? Here’s the link: http://www.maple-films.com/jrr-tolkiens-the-hobbit/the-final-version-of-durins-folk-and-the-hill-of-sorcery-is-now-available

It takes the ‘Thorin-centric’ footage that you’re talking about and edits it together into a separate companion piece to the Bilbo-centric material that you see in the Maple Leaf and M4 Book Edit.

I think what you’re suggesting, adding two substantial Thorin-centric prequel sequences into M4 The Book Edit might possibly undermine Bilbo’s story rather than improve it.