But, I in a way int kind of makes sense.
/bin and /sbin, needed for system boot. /usr/bin and /usr/sbin for normal runtime.
's' for items regular users do not need to run, remember, UN*X is a multi-user system, not a one person system like macs, windows and in most cases Linux.
Nowadays most Linux systems boot with initramfs, that is a compressed image that includes everything the system needs to boot, so you're basically saying /bin and /sbin is useless.
Not always (raise your hand if you've had an unbootable system due to a broken or insufficient initrd).
In retrospect, the whole concept of the initrd seems like an enormous kludge that was thrown together temporarily and became the permanent solution.
What seems bad about it to you? Initrd means you only need /boot (or equivalent) to be working at boot time, which seems nice to me. And looking at mine, the image is smaller than the kernel, so it's not wasting a ton of space.
Sure it could be blamed on shitty distro maintenance and development but a better architecture would be putting essential things like filesystem drivers in /boot without this extra kludge of rebuilding an initrd (that you hopefully didn't forget to do before typing reboot) which depends on a pile of config files set just right (and oh by the way different in literally every distro).
Rebuilding an image isn't a big factor there, it's a tradeoff between making setup a bit more annoying versus making it a bit easier to manage your boot files.