In my opinion as a Halo fan the main problem with 343 Industries is that at his core there was a small cadre of original Microsoft/Bungie employees promoted well beyond their capabilities. Let's remember that Kiki Wolfkill, Frank O'conner, etc were basically low-mid level managers in charge of IP licensing issues when Bungie was in charge of Halo. They were the guys dealing with the contracts for the Masterchief action figures, drinks, comics and books.
When Bungie wanted out of Halo for Destiny, 343 Industries was created around that small cadre of Microsoft/Bungie guys. They found themselves in charge of high-budget sofware development studio without any real experience or backgound. I'm afraid they were totally out of their league. Add to that that the original Xbox One/Microsoft strategy was making a lot of emphasis on TV, movies, shorts, etc., which was the "forte" and real passion of this cadre.
I'm sure they had little saying on technical issues, but they were probably powerful enough as to kick out of the company any discording voice. It's clear to me that the tech guys that made Halo 4, probably among the 3 best looking games of the entire X360/PS3 generation, weren't there anymore for H5/Halo Infinite.