This weekend, one of the directors of these movies, Bruce Sinofsky, passed away after struggling with diabetes. Metallica has a nice story up on their website about Bruce,
"Our thoughts and prayers are with Bruce's family and friends. We will miss Bruce. A courageous man with deep empathy and wisdom who wasn't afraid to dig deep to tell the story.
Go check out the whole post on Metallica.com
I don't know if you've seen the Metallica documentary, "Some Kind of Monster", but you really should.