In 2008 Apple revolutionised the laptop. And the funny thing is, no one knew it at first. The MacBook Air was a radical rethinking of what a laptop is expected to be. A distillation of utility, sacrificing power and expandability to become an exceptionally portable computer. But it was almost impossible to customise. Apart from a marginally faster processor and the option for more expensive flash storage, you took what Apple gave you.
The closed system paid off and Apple's production lines continue to be simplified. Consumers love the great battery life of the Air and a similar change is taking place with the MacBook Pro with Retina.
And now we see the new Mac Pro. Sleek, shiny, powerful. The Kubrick ideal of an alien waste paper basket. And despite the protests at the lack of expandability, Apple's goal seems clear: a single purpose device that performs it's one task exceptionally well. Apple is providing it's pro users with a great CPU (why only one socket I'm not entirely sure) and a staggering amount of GPU power. And alas these pro users do find themselves with niche requirements, but Apple seems to be insisting that if the computer is simplified then the expandability will fulfil the odd use cases that arise. It's worked well for them so far.
And so now the Mac Pro completes Apple's simplified product line. The reduced customisability is a huge benefit to Apple's bottom line and it demonstrates Tim Cook's unparalleled ability to manage operations. The Mac Pro is once again at home with the rest of Apple's products and should stay that way for the foreseeable future. You must just learn to love the trashcan truck.