Interesting - CP/M has a fixed sector size of 128 bytes. In CP/M 2.x, if your physical sectors were a different size, you'd have to implement deblocking code in your BIOS. CP/M 3.x still used 128 byte sectors, but supported specifying the physical sector size and would do the de-blocking for you.

I'm guessing MSX-DOS uses the 128 byte records/blocks to make it easy to read foreign disks and to be able to create disks readable on other platforms?