I think there's one major point everyone's overlooking.

This is a filler arc. It's not meant to be 'life-changing philosophical storytelling' like Endwalker was, or a 'flawlessly written post-apocalyptic isekai' like Shadowbringers. It's basically "Hey, we need a short story involving an established threat, to lead into the next major story arc. I know, let's do an FF4-inspired story that deals with the voidsent, they've been quiet for a while".