I'm not trying to sound harsh and just have to respectfully disagree.
I don't use Lumina because I don't use DEs, but the looks of it are just right. It's not a regression like most "styles" these days where it's impossible to know half the time what's an interactive widget, or why suddenly the designers think large empty white spaces and large widgets and titlebars are a feature. If I'm at a desktop, I need a desktop environment, not a tablet experience.