Why are the Thunderbolt cables so short?

Hi –

I recently purchased a Blackmagic GPU to work with my new MacBook Pro, however, I found it extremely odd that the Thunderbolt cable that it came with was only about 1.5' long. Only ideal for desks with a ton of real estate, if you're forced to place the unit down on a shelf – like I am – you really need a longer cable. I get the part that it's quasi-mobile and the idea is to be sitting at your local coffee shop cranking out heavy graphics and video, but I'd much rather deal with a lengthy cable than purchase something else on top of my rather significant budget drain. Let's face it, a twisty-tie is FREE!

BTW, on the Blackmagic eGPU, a USB C cable is not a replacement for the Thunderbolt 3, which is odd, they both fit perfectly and I cannot see where one has more pins than the other, so if anyone has answers to this conundrum they would be greatly appreciated!

Thanks!