alt Hacker NewsSiracusa—probably best known here for doing fabulous OS X reviews for Ars—is a co-host of ATP. He is also known is such circles for having Mac Pros, and using them for a long time (sometimes by choice, sometimes by circumstance). He thinks Apple should make a Mac Pro, not necessarily because it's a big seller, but because he thinks Apple should make a "best computer," much in the same way car companies might make a car that will never sell but pushes engineers, etc.
They made a shirt. It was fun.
Ages ago, when new Mac hardware came out, I'd amuse myself by putting together an "ultimate Mac workstation" in the configurator --- once upon a time, one could hit 6 figures pretty easily --- these days, well I panic bought a duplicate computer because I was worried a chipped/cracked display was going to make it unusable (turns out a screen protector has worked thus far).
I agree with the reasoning, and would like to see Apple continue to make aspirational hardware, but maybe the mainstream stuff is good enough?