Huh. Forgot about the Marathon Man achievement.

: Meanwhile, the motion comic style for ODST,

Were those really motion comics? They were just a sequence of blurred surveillance footage.

: Anniversary, and Halo 4
: accessible in the game (I know, I know. Just imagine it too) is
: straightforward as they generally concern events that are happening at
: this very moment or have great meaning to the story we're experiencing
: while shooting people.

Strictly speaking, only the Halo 4 terminals and a few Anniversary terminals directly tied in with the main story. ODST and most of the CEA terminals were backstory or side-story.

The funny thing is, by this logic the CEA terminals weren't worth making into motion comics because they were just backstory, when the subject (Evacuating vast swaths of Halo's landscape into orbit!) clearly warranted visuals.
Halo 4's terminals had to be visual for accessibility, but they didn't depict anything worth making visuals for.

: Of course, they may not necessarily have the depth
: that the revelation-heavy text Terminals have, but they are far less
: likely to take you entirely out of the experience (Yeah, I know. Shut
: up!).

Nah. Still not seeing it.

: Since I'd imagine that these text-base Terminals are fairly cheap and provide
: little burden for the studio, I don't see why we couldn't have both
: scattered throughout the games.

Probably because the executive producer of the Master Chief Collection thinks it's boring to have to read text in games. 343i went to all the trouble of getting voice actors for every scrap of intel you stumble across in Halo 4, don't see why it will change.