Comment by foohbarbaz

From a developer standpoint. I could get a minimal output via a serial port with a few lines of assembly on a bare hardware.

USB requires a lot more work and on Windows the API is atrocious. On Linux the API (libusb) quite a bit nicer, but still a bit of work.

The plug and play part, device naming and unique identifiers are a special "joy" of USB.

If serial port is sufficiently fast I'll take it any day over USB.