1. It is likely that the passive components are chosen to match the specifics of the cable. This would be more expensive to create with adjustable balancing. 2

1. It is likely that the passive components are chosen to match the specifics of the cable. This would be more expensive to create with adjustable balancing. 2. This also gives them the ability to have longer haul optical cables without changing the motherboards, the optical transceivers will be inside the cable. 3. None of the ESATA ports on any computer I have ever owned has never seen a plug. All of the firewire ports are empty. Probably 2/3 of the USB ports are empty. If Thunderbolt goes the way of these, why not move the circuitry out of the empty ports?