Oh please that's pure sophistry.
It's because people can go to Dell, configure a pretty sweet box that is all the computer they need for under 2K then go to Apple looking for the equivalent and see the MP strating as 2.5K that the whole MP is more expensive than Dell argument exists in the first place.
But when you buy an Apple box you're not just paying for the hardware, you're paying for the software too, everything from the OS to iLife, and this software is leaps and bounds above anything you get from Windows. Unless you consider all the worthless sharware that comes with Windows, because that stuff rocks!
The software is where it's at, but most folks don't care to look at that, they want to compare Apples to Apples whereas, in my opinion, comparing a Dell running Windows to a Mac Pro is Apples to Oranges.