Doom 4 was "a lot more cinematic," and had "a lot more story to it, a lot more characters around you that you were with throughout the course of the gameplay," id Software's Marty Stratton says in the video. "It was definitely a twist on Doom that took it into a much more cinematic, much more scripted type of experience."
It was "awesome," in the words of Hugo Martin, formerly of Naughty Dog, who served the creative director on the 2016 release of Doom, but it didn't fit the mold.
While I didn't particularly enjoy the new Doom and likely would have had a better experience with this unreleased version by the sounds and look of it, id's focus on delivering an amazing experience to the hardcore Doom fans is commendable. It's rare to see a studio take a chance like they did and start to whole thing over to please the core fanbase.
The full documentary is available to watch right now on YouTube.