What are motion comics good for? Well, I've seen them used for decent cutscenes in Homeworld and Company of Heroes. One is a game about space battles with hardly a human in sight, the other had some great scenes of entire fleets of troop planes and gliders.

The Halo 4 Terminals? Query whether they were cartoons or motion comics, but there was nothing they conveyed that couldn't have been better done in text.

: Puppet shows used to get a lot more respect.

Then Jim Henson died. And Gerry Anderson, half a year ago.

: how? why does it matter who the the people making these (motion comics or
: cutscenes or terminal content) have as their immediate boss?

Oh, Hell yes it matters.
Just out of curiosity, have you ever worked in an industrial setting? Ever build anything?

Contractors are great. Don't have the expertise to build something? There's someone out there who can make it for you. Or design it for you.
The drawback is less control. Less control over quality, less control over what's getting done, less flexibility when adapting to changed plans.

Think about this. If the cinematic department was in the building, and the writers wanted to make a change to the dialog, it's just a walk down the hallway to discuss it. Now, if the guys who are doing the cutscenes are in New York, hope you like teleconferencing and putting up with the difference in time zones. Oh, and did the art team decide to change the Didact to a less stupid-looking model? Yeah, that's going to cost extra to redo.

You're probably going to say "Then you should wait until things are finalized to commission the cutscenes." But that's the point: You're losing flexibility, and I haven't even gotten into problems of quality control.

: why would
: putting more work on people in 343i, or hiring new people mostly or only
: for that, be better?

Accountability. Networking. Company culture. The convenience of one team being able to converse with another team just a few rooms away.