> You know, like almost every Unix system for the last thirty years.
Ahem, like, Solaris, the most used Unix(tm) system, where /bin is symlinked to /usr/bin since many many years? Which other Unix systems do you mean? HP-(S)UX? Are there people still using it in relevant numbers? AIX? Should we then take smitty and AIX's configuration concept as a guide as well?
The split of / and /usr has been arbitrary since quite some time. It's much more important to work on being able to mount / read-only or over the net (with a local /etc partition), IMNSHO.
While I dislike the attitude of the systemd developers quite often, in this case (and in the introduction of /run) they're right. Actually, they bring it in line with one other major Unix system out there, not seperate it from Unix-land.