Things are getting out of control. Some of my non-technical friends are already moving into 16 GB of RAM on their new laptop purchases. For surfing the web and watching movies...
The worst thing is not just memory consumption, but sluggish UIs. Everything is turtle slow. I notice a significant lag when typing on their machines no matter how much RAM or CPU you have.
I run a WM (XMonad), Firefox (vimperator), a terminal (urxvt) and Emacs, with no actual desktop environment (but all services, including firejailed applications). Without opening Firefox, I'm comfortably below 200 MB of RAM. And Firefox is not a memory hog either, if setup and used with care.
Even more, before starting X, I'm around 128 MB of RAM, yet I can do most stuff inside a text-mode Emacs.
An additional benefit is robustness. With fewer components things hardly break, and when they do you can easily fix them. Especially if you use a Nix-style package manager and system configuration.
Not a setup for everyone, I know, but an average HN reader will have no problem putting it together. If friendlier GUIs are still your preference, I believe some lightweight Linux desktops are worth a shot. Last time I tried Xfce, it was simple and lightweight. Even my old dad was able to adjust to it quickly.