Only Firewire, Ethernet and USB were options. USB makes perfect sense.
But, SPDIF & high end sound cards WERE available. Why do you not advise that all agreed engineers wanted an idiot proof solution that did not require opening the computer?
Firewire was better, as that is what the proaudio world embraced (of the 3 you mentioned, only because ethernet was a little behind the times, then). USB was CHEAPER to implement. This is why everyone things USB is the way to go - it was cheaper and easier for the engineers to implement.
But, SPDIF & high end sound cards WERE available. Why do you not advise that all agreed engineers wanted an idiot proof solution that did not require opening the computer?
Firewire was better, as that is what the proaudio world embraced (of the 3 you mentioned, only because ethernet was a little behind the times, then). USB was CHEAPER to implement. This is why everyone things USB is the way to go - it was cheaper and easier for the engineers to implement.