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.
Eh, kinda. That's where "essential" .ko modules are packed into - those that system would fail to boot without.
Alternative is to compile them into kernel as built-ins, but from distro maintainers' perspective, that means including way too many modules, most of which will remain unused.
If you're compiling your own kernel, that's a different story, often you can do without initrd just fine.