I'll wait for real-world tests before dismissing the concept
Curiously, this article from eighteen months ago seems to predict this new Mac Pro, suggesting the concept isn't too alien to video production professionals:
"The concept proves with enough RAM and a powerful processor, Thunderbolt could enable smaller Macs to do the work of a Mac Pro. Hard Drives, PCI cards and everything besides the processor and RAM can now be connected via Thunderbolt rather that being built into the box.
Apple could modularize for their Pros. Think about starting with a Mac Mini with a XEON Processor and lots of RAM (OK, the cooling stuff might turn it into a cube)."
And that was using the less flexible Thunderbolt 1, not the newer TB2. These guys also seem to find TB for RED Rocket acceptable:
As for desk clutter, the people who are processing this much video are likely to have a rack mounted solution for storage already. Should a Mac Pro fail, it is quicker to plug a spare machine (even a Macbook Pro) into the Thunderbolt than it is to swap the drives (and exotic PCIe cards) out of the dead machine, allowing the studio to get on with chasing that deadline.