The aesthetic of Solution 9 really does nothing for me. I've never liked that kind of cyberpunk "everything is a billboard" setting. It's whatever; this wouldn't be the first time FFXIV has reached into tired genre tropiness (Pandaemonium).
My bigger issue is not with how it looks, but how it begs a lot of lampshading in the story. I really struggle to imagine how we spent an entire saga fighting a transcontinental technological superpower and transuniversal threat to the entire universe, and had never even heard of this city which is more advanced than anything we have ever seen on Etheirys. Even if they do manage to explain it away, it is likely to be an unsatisfying explanation.