Key practical purpose is to gauge ROC military response time and readiness. How many planes do they send to intercept us? How fast did they respond to aerial/naval assets congregating in key locations? Which radars are on and what can we gleam from the SIGINT mission etc.
Again, they don't need to do that with media coverage nor does it need to be done in this manner.
I think everyone should just accept that what is high profile and useful signaling for people in the general public is not necessarily that significant in actual conflict or actual high end military training.
It seems the height of arrogance to me to think that we have the right to observe training and operations that are actually important and sensitive.
This is a form of bread and circus, and not even that large in scale at that.