With how long they make the hoods on these vehicles, they surely could have made it fit. Each new TNGA-F vehicle has a ton of wasted space in the front.I think it has to do with packaging. An I-6 is longer than a V8 and encroaches on the pedestrian impact protection zone. But there has to be a way to make it work. And it saves a cylinder head, a second turbo, keeps the hot side hot and the cold side cold, etc. All have benefits. Plus the homage to the 80 as you mentioned.
For the impact zone, they design the motor mounts to give way in the event of a collision so the engine gets pushed under the vehicle rather than into the cabin.
It’s like they designed the motor for the LS 500 (which would have a problem fitting an inline 6), and then cheaped out and threw a slightly modified sedan motor in a truck platform.