It's not lipsyncing, or voice acting. It's not English versus Japanese voices. It's the dialogue, the flow of dialogue, the 'acting'/animations of the characters in those cutscenes which make them easily head and shoulders above the FF15 cutscenes.
The 15 scenes are just not good dialogue or performance wise. The scenes I posted flow. They're not stilted. The characters have facial expressions and body language that match the moment or their lines. The camera captures the above and the focuses of conversation better. And I'm not sure how much more serious scenes get than a guy finding out his country has fallen and his father was killed. Aren't you just making excuses for poor cinematics because you're already too invested in the product?
Again, you posted longer dialogue exchanges in more serious cutscenes. The ones in the Gamespot video are cobbled together scenes that were made so that nothing is spoiled.
And I don't feel like those scenes in the other video as a whole are much better. There is better flow, yes, but that is due to what I mentioned.
If we are really going to get nitpicky here, gaming has a long way to go to reach the quality of movie acting. There are games, such as Witcher 3 and Uncharted 4 that reach near that level, but what you posted is not, and is indicative of how video game delivery is done in general.
Once again, the scenes in this video of XV are cobbled together, and don't really showcase the same type of conversation in the dialogues you posted. We don't know why Ardyn, for example, is standing there or why he says what he says. It is cut out of a longer conversation, which makes it harder to understand the context. All the other scenes start at the beginning and go on long enough to get proper context.
