But there's no need for a tubular design in a liquid-cooled machine. The on eyou cite, for example, is oil-cooled.
The Wilkes is actually air cooled and is the most efficient air cooled super computer in the world, and the 2nd most efficient overall. In the article, it appears you may have read it too fast. The oil cooled machine referred to is the one the Wilkes came in 2nd to in terms of efficiency and was built by a team in Tokyo.
However, your actual point is valid. Liquid cooled machines are shape neutral when it comes to cooling efficiency.
The original point made - asking why other high end pro machines are not also tubular designs and then citing the Wilkes super computer is a bit misleading and disappointing. That is a comparison between a huge supercomputer (the 166th most powerful computer made by man) that fills several hundred square feet, and a professional desktop workstation that fills less surface area than a tea saucer on a desk. Not really the best comparison.
Maybe the reason nobody else has done it yet is because they haven't been able to? Haven't thought of it? Didn't think it would be successful in the market? It sounds too much like Arthur Rock in the early 80's to be honest. The personal computer will never take off, etc. Or what about the music player before the iPod, the smartphone before the iPhone, the tablet computer before the iPad. Have a little bit of imagination.
If there is one thing that Apple has done in its history that has made it great, it is not being afraid to push the envelope on design language. Just look at the Macbook Air as another, slightly less dramatic, example - now literally every major and most minor computer manufacturer has an Air clone out there and a whole new class of laptop, the ultrabook, was created, killing the netbook craze overnight!
Have they made mistakes and/or failed on occasion with design and/or hardware choices? Heck yeah! But that list is a lot smaller than its counterpart.
Really a bit early to pass judgement on a machine that isn't even out in the wild yet. There seems to be overwhelming excitement from the demographic that are actually going to be in the market for these- seems most of the negativity is in general coming from people who were never int he market for this category of hardware in the first place and don't seem to know or want to educate themselves on how they will or are intended to be used.
Correct me if I am wrong!