No, people do not "forget" the difference between Xeons/i7s and ECC/non ECC. It's that the price differences are not that big. We just bought 24 gigs of Mac Pro ram for under 200 dollars. The Mac Pro comes with ...3? The entry level CPU is about 300 dollars.
The base level Mac Pro is a complete rip off. It's a sub 1000 dollar machine priced at 2499. It's nothing less than shameful.
It was stated pretty well above. The entry level model is priced higher so as not to cannibalize the iMac line. The higher level Mac Pros compete quite well with other manufacturer's workstations. Not to mention that the iMac line has benefitted from Intel CPU refreshes in contrast to the current MP.
And regarding "sub $1000", people underestimate the value of the case, power supply, and tray-based motherboard that they use. These things are all value adds, and while they don't contribute to the performance they certainly contribute to the machine's price. They also contribute to its value in the target market. There are no sub $1000 PCs that are built this well.