Agreed. On a small notebook display I tend to work with one or a small few windows at a time, usually taking up most or all of the display area. Aspect ratio is highly relevant to my experience there and actually guides the aspect ratio of my windows.
But on a large desktop display, I end up with lots more windows at any one time, including lots of small windows that stay around and in one place for a long time: things like notes, feeds, things to come back to, etc. And, in that large space, I can size each window as large as I want, so I much more often can use a natural-feeling aspect ratio for its content. In other words, large displays are the only ones for me in which a "desktop metaphor" GUI actually feels and functions like a desktop. So, on a large display (aside from games/movies), I don't care too much about aspect ratio, I'll fill up the edges of whatever space I've got.
But on a large desktop display, I end up with lots more windows at any one time, including lots of small windows that stay around and in one place for a long time: things like notes, feeds, things to come back to, etc. And, in that large space, I can size each window as large as I want, so I much more often can use a natural-feeling aspect ratio for its content. In other words, large displays are the only ones for me in which a "desktop metaphor" GUI actually feels and functions like a desktop. So, on a large display (aside from games/movies), I don't care too much about aspect ratio, I'll fill up the edges of whatever space I've got.