hi
i think xcom used Matinee In order to achieve the effect of a dynamic camera (they said in one of the interview’ they wanted a movie affect), the effect creates an element like a camera in the film(cutscene) - the camera has dynamic movement or crane movement and you can not mimic this effect only with code, also camera animation and timeline alone will be very limited.
So the benefit of the Matinee, or rather the ability of the matinee is to bring the transition to the shoulder camera that will be seen as an action movie (note that in xcom the camera is not static and you have a fell of a movie)
What has written sounds a great idea - maybe will not bring the same result but definitely more simple i think.
Unfortunately, I did not try to connect Matinee to code in such a situation so I can not help you with that, sorry
leo