I recently upgrade to a 5k imac... and it's an absurd amount of space. I don't see the point in griping about aspect ratio when it's merely size and density that we really want.
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.
My current fave monitor at home is my ca2008 Dell 2405 with all it's 1920x1200 glory. The Pixel is second, but a distant second because the screen is so small that if you actually use the full resolution you can't read a darn thing.