Steve's 2x2 matrix with portable vs desktop on one axis, and consumer vs pro(sumer) on the other axis, was announced and filled around 1998.
It was populated initially with:
iBook, iMac;
PowerBook, Power Mac.
Later:
MacBook (Air), iMac;
MacBook Pro, Mac Pro.
The "pro" version had always been accessible to consumers. It was a bit more expensive, but if you wanted more power and expandability than the consumer model you could get the low-end "pro" model easily. And, yeah, the "real" professionals could spec it out and get a high-end pro machine.
Now, this latest Mac Pro is a machine that's out of range of your average prosumer and even pro, even in the lowest configuration. That's what upsets people.
> This viewpoint is the side-effect of Apple's lifestyle brand marketing.
No, the anger is born from an expectation (namely, that prosumers can get the low-end pro model) that well predates the whole life-style brand marketing (iPod 2001, iPhone 2007).