> It’s not actually good usability.

They're really great on systems that let you hold a modifier key and then a mouse button to drag windows around... rather than requiring you to find the very-small-compared-to-the-size-of-the-entire-window portion of the window you can click to change the window position. They get even better when you're on a system that reliably remembers the position of application windows.

Folks who have never used a system that lets you relocate and resize windows without first moving your mouse cursor to "blessed" regions of the window absolutely do not know what they're missing.

> ...they have been unfashionable...

Fashion is for people who love doing busywork. Where fashion gets nasty is when that busywork makes a bunch of work for everyone else.