Isn't a significant chunk of OS memory usage caused by the desktop UI? If we're talking about servers, I'm guessing it would be because of drivers and more built-in functionality, some of which is rarely used.
Yeah — the image buffers (screen resolutions) are bigger, we run more apps, more advanced desktop environments… also in the old days (before OS X, Compiz (fun with desktop cubes!) and Vista Aero) people used to run without compositing, which meant one common image for all apps to draw into.
Just booted my laptop (FreeBSD -current amd64, 1366x768 display) and started X: only 204M "Active" memory. Of the 204M: 60M is syncthing, 39M compton, 31M Xorg, 11M i3bar, 11M polkitd, 10M i3, 9M dunst, 5M wpa-supplicant… Not counting syncthing that's 144 megabytes. I think that looks reasonable. You can go lower and optimize for low memory (no polkit, no compton — 94M) or go higher and optimize for usability and fancy UI features (install gnome :D)
Just booted my laptop (FreeBSD -current amd64, 1366x768 display) and started X: only 204M "Active" memory. Of the 204M: 60M is syncthing, 39M compton, 31M Xorg, 11M i3bar, 11M polkitd, 10M i3, 9M dunst, 5M wpa-supplicant… Not counting syncthing that's 144 megabytes. I think that looks reasonable. You can go lower and optimize for low memory (no polkit, no compton — 94M) or go higher and optimize for usability and fancy UI features (install gnome :D)