It struck me as odd some years ago when I upgraded to Win 7 64 bit it would not take just any exterior CD drive. I had to buy a Samsung CD to get it to work because Samsung had developed the new drivers.
But my 20 year old exterior floppy drive worked with the new program. So perhaps some of that is going on, floppy drives survive the updates and require no new drivers.
Not certain why an OS installation requires a floppy disk. I am referring to XP. Haven't had to install Win 7 from scratch.
Who knows... maybe a floppy drive is easier to support, drivers, etc. than a DVD drive when installing the OS.