Dude, I was thinking the same thing.
On one hand, less time making scenarios and props to make a single video, having an already functional engine to have scenes/ proper game over screens. having fewer issues when playing said scenes and more camera positions.
On the other, it would take time to model props/models that (probably) would only show up once per scene, coding for playing said scenes and being more restricted on what you can do with them (either poses, setting, actions, etc idk).
It suddenly came to me the other day when I saw the "Nile Game Over" tape in-game or the Poppy equivalent and asked myself "Hey, the devs have already models of these characters. Why bother making an entire scenario just for one video if they could theoretically make it inside of the game?"
Now, again, I'm no game dev. I have no clue how big of an overhaul that would take, or even having it implemented since the beginning. What I can say, though, is that having a scene played out on what seems to be a test area with plain, beige textures and no flair whatsoever alongside Nyle sticks out like a sore thumb more than it has any right to be.
(If curious, I think it's either the first or second Nyle tape. I'm positive it's been there since earlier versions of this game, that's why I mention it).