With this change /usr is basically the same as \Windows, the whole OS is in one directory except we are smart enough to pull out the dynamic info into /var and /etc. Now we just make /etc a symlink to /var/etc and we get the whole operating system down to two directories, one per host changing information and one static read only binaries, libraries and documentation.
Of course they are also busy repolluting / with new top levels, otherwise we could look forward to a root with only:
/boot for the boot loader, kernel and initrd
/home for users
/media as the modern replacement for /mnt
/opt, probably can't get 3rd party vendors to give up on that one.
/proc for the kernel
/root since it probably can't go in /home/root safely
/sys for the kernel
/usr for the OS
/var for the OS
Plus symlinks for /bin, lib and /sbin. But I currently have /cgroup, /run and /srv cluttering things up. Why did we need those others in root and not somewhere under /var or /sys?