I agree.Presuming upgradability and a requirement for a Mac, a Mac Pro is the cheapest option. So long as you can upgrade the weakest pieces a Mac Pro can easily be a 5-year computer for personal use. An iMac would have to be replaced every 2 years or less to keep up. So you'd need three iMacs over the life span of a Mac Pro. That's more expensive and much more wasteful.
Of course, that's presuming upgradability, which includes the video card. If Apple really expects their customers to buy all new computers for every minor upgrade they should expect Greenpeace to be knocking on their door again.
It's also a good reason for a mid-range tower. 4 and 8 cores is overkill but 2 and 4 cores with upgradability would be just right for economically (and environmentally) minded consumers.
I prefer to have my PowerMac G5 in my home office for graphics work, act as a hub in my digital lifestyle and be my work horse.
Being that it is my hub, I like to have the options to swap out pieces should I need the good old fashioned "bigger" or "better". I have swapped out 3 HDD's since getting the last gen PMG5, each swap moving larger and larger, while taking the last biggest HDD and moving that to the second HDD bay and the smallest one is now serving duty as my Time Machine in an external enclosure. I've also added and upgraded to 2 video cards running 3 LCD monitors in extended desktop.
Plus I like having the safety net of knowing that if one of my HDD's goes bad I can rip it out myself and pop a new one in from off the shelf down the road at the mall in a matter of 30 minutes and be up and running again.
Can't quite do that with a current iMac..... why Apple took that ability out of the iMac is beyond me.