I need the power of a Mac Pro for my 3D animations. I need something that can render fast and capable to support lots of polygons when i do rotations. My Macbook Pro handles well for that but it's not enough and i had to wait a bit longer... I refuse to install Windows on my MacBook Pro because it might mess my little system, my track pad, keyboard... I need a Mac Pro so i can install Windows freely in order to run 3D programs that OS X don't have such as Autodesk Softimage and 3D Studio Max.
I rather have a machine with a kick ass new look that will last for years to come and only to worry about upgradability of the internal for future proofing.
And i wouldn't feel comfortable if i purchase a PC tower only to run those programs because all my hardwares are apple compatible.
"I'm vain and my priorities are bizarre" would have been SO much less typing for you.