A loaded iMac costs several hundred dollars MORE than a base model nMP. More importantly, it uses laptop, not even desktop, let alone workstation, parts--all so that it can house a screen that many people (myself included) do not need, and absolutely do not want.
I do agree that Apple seems relentlessly to ignore, obviously intentionally, those of us who want a $1,500 headless desktop (myself included). They must continue to conclude that this population will either migrate to a Mac Pro and spend the extra money, or be satisfied with a Mac Mini, because those are the only options that fetch Apple the margins it wants to earn, and it is willing to sacrifice some lost sales in order to make those margins, which of course it has every right to do. Apple has no obligation to satisfy my needs. None. It has the obligation to its shareholders to make decisions likely to earn it the most profits it can while building a viable business model. In that sense, from every indication, it is meeting its obligations quite well.
Valid points. I suppose my comparison with a base 4-Core should have been better written (example a reasonably equipped BTO 4-Core w/ upgrades).
Out of curiosity, how would a base nMP compete against a well equipped (or perhaps loaded) iMac? What do you believe the price difference may be?
I disagree a bit on "why" Apple seems to be neglecting a midtower/etc system to fill the gap between an iMac and base nMP. There's a decent market clamoring for such a system, either gamers (was quite surprised to learn they make a good deal of money testing/developing products, now even more so in the OS X market), prosumers who need more BTO options, even residential customers.
I switched my father, now 70, to OS X with a PowerMac G5. At that time, most tech savvy people I knew didn't like the idea of an all-in-one system, especially the built in display. Moving from a mid-tower Windows system to a similar Mac made sense, allowed him to use his monitor, upgrade the system, having more "freedom" with its use.
I suppose my point is that there are many in this "grey area" who would jump at a reasonably equipped Mac mid-tower, with price points similar to the PowerMac G4/5's. Apple does not always know what is best for the consumer, Jobs almost killed the Mac Pro until he was talked out of it, and the iPhone 5c hasn't been the most successful product launch. Sometimes, the old proverb, "the customer is always right", does ring true.

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I don't think they expect many pros to go for the base model but offer it anyways to possibly entice people in to the pro market.
Absolutely. I would be enticed, but it would be a downgrade from my current Mac Pro5,1 and I would have to spend more on external chassises for my internal drives, etc. At that point, I may as well bite the bullet on the 8 or 12 Core.