/usr is a relic of the times when unix systems were big hulking monsters the side of fridges. and hard disks the size of washing machines. You kept a separate /, /var, /usr, /home, etc because you had a lack of space and because disks kept crashing.
That's no longer the case. Even for the largest 4096cpu numa system you just throw the entire OS on one partition, with a separate home/data disk.
I'm sure the developers have some neckbeard reason why it has to be /usr and not / but surely user friendliness is not it.