> it feels like Mac's UI is optimized around the assumption most users won't expand windows to fill the whole screen, but rather leave them half-sized somewhere in the middle
IMO, this has been their assumption for years, and it actually turned me off when I tried getting used to Mac circa 2006-2007. Coming from Windows at the time, I just couldn't get over a weird anxiety that my application window wasn't maximized, because it didn't look like it completely snapped into the screen corners.
Now, using 34-inch ultrawide monitors almost exclusively, I never maximize anything... it'd be unusable.
While I don't maximize anything on a monitor that wide, I do appreciate Window's snap to half/quarter functionality for monitors that wide, and I wish Mac had the same ability natively.
I constantly stretch windows to maximum height.
I maximize windows of graphics and video editors.
I just installed Kubuntu last week so I could get the additional shift-drag targets to split my 34" ultrawide into 3 sections, or bump to the edges for the half filled.
Ultrawide without a virtual screen manager is a missed opportunity. Maximize window is still very useful with virtual screen areas on large screens.
Brother, I have 42 inch 16:9 and I always maximize everything.
As a 38" ultrawide owner myself, I use vscode or intellij maximized most of the day, depending on the codebase I'm
Browsers only ever get maximized to the left/right half screen for me too
Which is something macos should really improve on though, the ux is pretty bad compared to Windows and Linux there