Great, now I can buy a Thunderbolt dock offering all the ports that a computer should already have! Okay, maybe for a laptop this could make a lot of sense, though personally I'd rather see more Thunderbolt display options with these ports built in for that purpose. I also don't see why they couldn't fit internal power in this device; it's pretty big for a bunch of ports and shouldn't have any major cooling needs; this just gives the impression of yet another "premium" Thunderbolt device that is cutting corners by not designing AC-DC conversion into the actual product.
Each HDMI connector integrates 19 cable pairs that must be of precisely the same length (and other corresponding factors) in order to accurately transmit the digital bits that make up digital audio and video signals. These bits must arrive at their destination in a perfectly synchronized fashion in order for the components on the receiving end to properly interpret the data. Therefore, all commercially available HDMI cables are designed, manufactured and tested to extremely tight tolerances before they can be emblazoned with the official HDMI logo.