Wow, this was a really cryptic-lore heavy update. It has earned a few rereads to pock out all the datails, and yet I'm sure I will miss some.
Now onto the vote.
Complexity, as many have guessed, it's most likely about strenghtening stand alone techniques. Not only in power but also in versatility. To create Champions.
The problem I see here is that we don't have a lot of those? The only ones that come to mind are the Gods of BKSD, and we have only learned 2 out of 4.
Most of our constructs techniques are about creating many minor constructs, an army of them.
Coordination, on the other hand is about seamlessly combinating the techniques from our multiple constructs arts: FVM, PLR, BKSD, maybe even FSS+ if it ends up including constructs in it.
Heck, I could even include WHR and our Roaming Moon Eyes as well.
The point is, that Ling Qi's fighting style includes combining a lot of constructs techniques at the same time. We see it all the time on the narrative:
Shadow beasts standing up with fancy clothing. Reveliers gaining icy talons. And so on.
Coordination would be the perfect answer to merge all that mishmash into a coherent battle plan. All our techniques strenghtening each other.
Not only that, it's also the option that works best when we are fighting with companions.
Like Yu Nuan's cloud doggy fighting inside our mist back in the Thunder Palace.
For me it's just a better specialization.