Yet the Mac Pro is ...
a) Round
A shape chosen for better cooling characteristics - they can get away with a smaller case, and a smaller fan to cool the same components that a square case would use.
b) Shiny
This is the only one of the items that really has little practical use. Yet what case maker WANTS a butt-ugly case? And in a design shop it looks better to have better looking gear.
c) Cool looking
This is only because it's small, but small has utility too. It means it's much easier to move around, and modern workers change workspaces more frequently than they used to. Have you tried moving one of the older Mac Pros? They looked great too but you sure wanted to leave them where they were.
d) expensive
That's not even right. For what you get it's NOT expensive, which is the whole point of the Slashdot story to begin with. It gives you a lot of power at a fair price, and some people do in fact need that much power. Anyone who does not can just buy an iMac.
There are a few rich people that will buy one just for fun, sure. But most of the people buying this system will do so because they have a PRACTICAL need for the power the system offers in a smallish form factor.