> texture in the window titlebars, I assume to give them physical-like presence and to encourage grabbing them.
That's called a visual affordance. Once upon a time it was canon that interactive UI items had visual affordance -- you could tell that you could interact with them at a glance, just by looking at them.
In MacOS There's an accessibility setting in System Settings > Accessibility > Display called "Differentiate without colour" that adds some extra affordances like on and off icons in the switches. I forget what else, but I always have it on because it makes things even more obvious in a way that it feels like OS programmers used to take more seriously in an era before the flat design idiocy.
There’s another option for high contrast that makes things look more like old Macs. I think it looks better, regardless of accessibility considerations.
That's called a visual affordance. Once upon a time it was canon that interactive UI items had visual affordance -- you could tell that you could interact with them at a glance, just by looking at them.